The Conservation Status of Trillium in North America by Mt. Cuba Center

The Conservation Status of Trillium in North America Clayton Meredith, Anne Frances, Amy Highland, Leah Oliver, Aaron Floden, L.L. Gaddy, Wesley Knapp, Danna Leaman, Susan Leopold, Tara Littlefield, Robert Raguso, Edward Schilling, Alfred Schotz, Anna Walker, and Kjirsten Wayman

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The IUCN SSC Medicinal Plant Specialist Group (MPSG) is a global network of specialists contributing within our own institutions and in our own regions, as well as worldwide, to the conservation and sustainable use of medicinal plants. The MPSG was founded in 1994 to increase global awareness of conservation threats to medicinal plants, and to promote sustainable use and conservation action.

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Acknowledgements We would like to thank the New Mexico BioPark Society for providing funding for this project and making this work possible. We would also like to thank Mt. Cuba Center for providing a venue for the October 2019 workshop, and providing funding to complete and print this report. In particular, we would like to acknowledge the help of Julie Miller Rugg (New Mexico BioPark Society Director), Amy Highland (Mt. Cuba Center Director of Collections), and Jeff Downing (Mt. Cuba Center Executive Director).

The views expressed in this publication do not necessarily reflect those of the IUCN, or other participating organisations. Copyright 2022 Mt. Cuba Center Reproduction of this publication for educational or other non-commercial purposes is authorised without prior written permission from the copyright holder provided the source is fully acknowledged.

Susan Farmer provided a wealth of unpublished information regarding the Trillium pusillum species complex. Spencer O’Bryan (Mt. Cuba Center) helped with assessments during the 2019 workshop. Amanda Treher (NatureServe) reviewed the Global Ranks of many Trillium taxa. Carrie Radcliffe (Atlanta Botanic Garden) provided additional information on the assessment for T. persistens. Kyle Filicky, Hugh and Carol Nourse, Jason Singhurst, Anna Strong, and the West Virginia Natural Heritage Program generously provided images.

Reproduction of this publication for resale or other commercial purposes is prohibited without prior written permission of the copyright holder. ISBN 979-8-9850471-0-3 All the photographs used in this publication remain the property of the original copyright holder (see individual captions for details). Photographs should not be reproduced or used in other contexts without written permission from the copyright holder.

Funding Funding was provided by New Mexico BioPark Society, Mt. Cuba Center, and NatureServe. NatureServe would like to thank the Bureau of Land Management and the Frick Foundation.

Cover Photos Front: Trillium sulcatum (E.E. Schilling) Back: Pseudotrillium rivale (K. Wayman) Design: Conrad Doborski

Dedication

Printed by Mt. Cuba Center

This report is dedicated to the memory of Tom Patrick, a foremost expert on Trillium in the southeastern United States. He was a student of the genus for more than 40 years. It began in the 1970s with his graduate work on Trillium [Trillidium] grandiflorum, his description of T. sulcatum, and continued while as a botanist with the Georgia Natural Heritage Program and included advancements in the life history of T. reliquum, assistance in describing recent species such as T. oostingii and T. delicatum, and supporting other researchers studying this complex genus. In addition to his work on Trillium, he was the first botanist in the Georgia Department of Natural Resources, authored Protected Plants of Georgia, a widely cited botanical reference, won the Georgia Plant Conservation Alliance lifetime achievement award, and was respected and admired within the botanical community.

Recommended Citation: Meredith, C., Frances, A., Highland, A., Oliver, L., Floden, A., Gaddy, L.L., Knapp, W., Leaman, D., Leopold, S., Littlefield, T., Raguso, R., Schilling, E.E., Schotz, A., Walker, A., and Wayman, K. (2022) The Conservation Status of Trillium in North America. Mt. Cuba Center, and New Mexico BioPark Society. Hockessin, DE and Albuquerque, NM

Contents Acknowledgements................................................................................................................................................................. 4 Funding.............................................................................................................................................................................. 4 Dedication.......................................................................................................................................................................... 4 Foreword .................................................................................................................................................................................. 7 Executive Summary................................................................................................................................................................. 8 Methodology...........................................................................................................................................................................10 Taxonomy..........................................................................................................................................................................10 Data Collection and Quality Control.................................................................................................................................10 Mapping............................................................................................................................................................................11 Results and Evaluation..........................................................................................................................................................12 Major Threats..........................................................................................................................................................................14 The Trillium Collections at Mt. Cuba Center.......................................................................................................................16 A note on the taxonomy of Trillium.......................................................................................................................................17 On western Trillium................................................................................................................................................................19 Floral scent, taxonomy, and ecology of Trillium in North America................................................................................. 20 History of Medicinal Use...................................................................................................................................................... 22 Information on the trade.................................................................................................................................................. 22 Ending the Trillium Trade in Commercial Herbal Products............................................................................................. 23 Species Assessments........................................................................................................................................................... 24 Pseudotrillium rivale......................................................................................................................................................... 25 Trillidium undulatum......................................................................................................................................................... 25 Trillium albidum................................................................................................................................................................ 26 Trillium albidum subsp. albidum............................................................................................................................. 26 Trillium albidum subsp. parviflorum....................................................................................................................... 27 Trillium angustipetalum.................................................................................................................................................... 27 Trillium catesbaei............................................................................................................................................................. 28 Trillium cernuum.............................................................................................................................................................. 28 Trillium chloropetalum..................................................................................................................................................... 29 Trillium cuneatum............................................................................................................................................................. 29 Trillium decipiens............................................................................................................................................................. 30 Trillium decumbens.......................................................................................................................................................... 30 Trillium delicatum............................................................................................................................................................. 31 Trillium discolor................................................................................................................................................................ 31 Trillium erectum............................................................................................................................................................... 32 Trillium flexipes................................................................................................................................................................. 32 Trillium foetidissimum...................................................................................................................................................... 33 Trillium georgianum......................................................................................................................................................... 33 Trillium gracile.................................................................................................................................................................. 34 Trillium grandiflorum........................................................................................................................................................ 34 Trillium kurabayashii......................................................................................................................................................... 35 Trillium lancifolium........................................................................................................................................................... 35 Trillium ludovicianum....................................................................................................................................................... 36 Trillium luteum.................................................................................................................................................................. 36 Trillium maculatum........................................................................................................................................................... 37 Trillium nivale.................................................................................................................................................................... 37 Trillium oostingii............................................................................................................................................................... 38 Trillium ovatum................................................................................................................................................................. 38 Trillium crassifolium................................................................................................................................................ 40 5

Trillium hibbersonii.................................................................................................................................................. 40 Trillium ovatum var. oettingeri..................................................................................................................................41 Trillium ovatum var. ovatum.....................................................................................................................................41 Trillium scouleri....................................................................................................................................................... 42 Trillium persistens............................................................................................................................................................ 42 Trillium petiolatum............................................................................................................................................................ 43 Trillium pusillum............................................................................................................................................................... 43 Trillium pusillum var. monticulum........................................................................................................................... 45 Trillium pusillum var. virginianum............................................................................................................................ 45 Trillium pusillum var. 4............................................................................................................................................. 46 Trillium pusillum var. 5............................................................................................................................................. 46 Trillium pusillum var. ozarkanum..............................................................................................................................47 Trillium pusillum var. 1..............................................................................................................................................47 Trillium pusillum var. pusillum................................................................................................................................. 48 Trillium pusillum var. 3............................................................................................................................................. 48 Trillium recurvatum.......................................................................................................................................................... 49 Trillium reliquum............................................................................................................................................................... 49 Trillium rugelii................................................................................................................................................................... 50 Trillium sessile.................................................................................................................................................................. 50 Trillium simile.....................................................................................................................................................................51 Trillium stamineum............................................................................................................................................................51 Trillium sulcatum.............................................................................................................................................................. 52 Trillium tennesseense...................................................................................................................................................... 52 Trillium texanum............................................................................................................................................................... 53 Trillium underwoodii......................................................................................................................................................... 53 Trillium vaseyi................................................................................................................................................................... 54 Trillium viride.................................................................................................................................................................... 54 Trillium viridescens........................................................................................................................................................... 55 Photos ..................................................................................................................................................................................... 56 Works Cited............................................................................................................................................................................ 67 Appendix A: All Red List Category and Criteria Designations........................................................................................ 80 Appendix B: All NatureServe Rankings.............................................................................................................................. 82 Appendix C: Red List Categories and Criteria................................................................................................................... 84 Appendix D: Table of Common Names Used in Text........................................................................................................ 85

Foreword Clay Meredith, Species Survival Officer for Plants, at New Mexico BioPark Society organized the conservation status assessments, the results of which inform this overall assessment of Trillium. A weeklong workshop at Mt. Cuba Center leveraged the field knowledge and analytical proficiency of fifteen North American plant scientists to review the findings and bring this assessment to fruition.

The transfixing beauty of Trillium belies their structural simplicity. These ephemeral woodland wildflowers, composed of three petals and three bracts, possess unique charm that has beguiled naturalists, collectors, and gardeners for generations. Encountered in the wild, Trillium catch the eye and imbue their habitat with an air of specialness, as if you have stumbled into a magical forest. Trillium also possess medicinal value, as an astringent and uterine stimulant, giving rise to the common name ‘birthwort.’ Under pressure from habitat loss, White-tailed Deer browse, climate change, and plundering, many Trillium are becoming less prevalent in the wild.

Given the uncertain and evolving conservation status of several Trillium species, this assessment is critical and timely. The results provide up-to-date information to guide the efforts of ecologists and restoration professionals, and to better understand the gaps in our understanding that remain to be investigated. This survey highlights the importance of ongoing fieldwork on North American medicinal plants and reaffirms the urgency of efforts to ensure their safe keeping. Thanks to all those who helped in this important effort.

And so it is with many plants of medicinal value. The Medicinal Plant Specialist Group of the International Union for the Conservation of Nature’s Species Survival Commission estimates that there are around 2,000 plant species native to North America that are used medicinally. The Medicinal Plant Specialist Group is charged with filling information gaps to accurately assess the conservation status of these species, identify habitats critical to their survival, and recommend management strategies to improve their prospects for the long-term.

Jeff Downing Executive Director Mt. Cuba Center

Convened under the auspices of the Medicinal Plant Specialist Group and the North American Plant Red List Authority of IUCN, this project brought together the botanical expertise of many of North America’s foremost Trillium researchers. Partner organizations including the New Mexico BioPark Society, NatureServe, and Mt. Cuba Center, made this collaboration possible.

Trillium grandiforum photograph courtesy of Mt. Cuba Center 7

Executive Summary Regions with the greatest richness of threatened Trillium taxa follow the trend of general species richness, but one area stands out in this regard. The southeastern United States is home to the greatest number of threatened species. This reflects the unique evolutionary history of the region, which served as a glacial refugium and consequently hosts many localized endemic species. The Pacific Northwest also hosts a significant number of threatened taxa, and recent genetic evidence has revealed previously unrecognized taxonomic diversity. Again, localized endemics in the region are the major contributing factor. Other regions hosting threatened species include the Sabine River basin and surrounding areas of Texas and Louisiana, and portions of the MidAtlantic extending from Raleigh to the Delmarva Peninsula. The latter is driven by the Trillium pusillum complex which is increasingly recognized as a diverse taxonomic grouping containing several threatened taxa. Using the narrowest plausible taxonomic interpretation, 32% of Trillium taxa are listed under a threatened category on the IUCN Red List of Threatened Species. NatureServe’s rankings resulted in 51% of Trillium taxa in North America in the Imperiled to Vulnerable categories. The discrepancy is due to NatureServe’s recognition of varieties and subspecies in some species which inherently increases the likelihood of detection of rarity.

The genus Trillium is made up of about 50 species worldwide with concentrations in eastern and western North America and eastern Asia. The diversity of Trillium in North America warrants special recognition because both the Pacific Northwest and the eastern half of the United States are centers of endemism for the genus1. Identifying the conservation needs of the genus is a high priority given recent taxonomic changes within the family, the number of species with small ranges which could be conserved through relatively minor interventions, and the need for coordinating action between a variety of conservation organizations. Assessment of the conservation status of Trillium is considered here to be a first step in the development of comprehensive conservation action plans for under-conserved members of the genus. Trillium, also known as Wake-robin or Toadshade, are wildflowers that are found in a variety of woodland habitats. They are long-lived perennial plants and are often slow to reach flowering age. Flowers are produced in March – June, though some species along the Gulf Coast flower as early as January, and some at high altitude in the west flower as late as July. Fruiting takes place in summer, and seeds from many species are dispersed by ants which are attracted to a highly nutritious appendage on the seed called an elaiosome2. Other important shared life history traits include floral self-incompatibility, and complex seed dormancy. The taxonomy of this genus is complex, but ongoing research is answering long-standing questions and revealing diversity in some species complexes. Trillium was formerly included in the family Liliaceae, however, it is sometimes placed in Trilliaceae3–5 or Melanthiaceae6, 7. The genus is split into two informal groupings that divide those species that have stalked flowers, the Pedicellate Trillium, and those species with flowers that have no stalk and are attached directly to the stem, the Sessile Trillium. Historically, a narrow definition of species concepts was accepted. Through the course of the 20th century, however, many of these names were relegated to synonymy1–3. Recent molecular evidence has resurrected several of these taxa and raised questions about whether other species might represent complexes of cryptic species. This evidence also suggests that two taxa traditionally accepted as members of Trillium are more accurately treated as forming the closely related but genetically distinct genus Trillidium. Throughout this booklet, the most current taxonomic interpretations are presented. Future taxonomic changes will likely alter some of the information presented here, but the authors have taken care to present several possible outcomes. Colloquially, the grouping of members of the genera Pseudotrillium, Trillidium, and Trillium have been referred to as “Trillium”. Due to the recency of taxonomic changes and the familiarity many have with this terminology, this volume will frequently refer to all three genera in the aggregate as Trillium unless specific distinctions are needed.

Threats identified in this analysis are quite varied. While threats broadly follow trends based on species range and biology, the slow life history and poor seed dispersal of the group make all taxa susceptible to some degree to population declines. Habitat damage caused by feral Pigs and predation due to the overabundance of White-tailed Deer threaten more taxa than any other factors. Other threats include competition with introduced plant species, habitat loss due to development, overcollection for medicinal or horticultural purposes, and climate change. Unfortunately, the quality of data supporting each of these threats is inconsistent. For example, while some introduced plant species are often cited as major competitors, namely Kudzu (Pueraria montana) and Japanese Honeysuckle (Lonicera japonica), both species may have paradoxical impacts through complex interactions with White-tailed Deer behavior. Data are also lacking for the impact of collection for medicinal or horticultural purposes. While anecdotal reports of collection for medicinal purposes abound, and a market clearly exists, few data exist regarding which species are harvested, and how collection impacts wild populations. Even instances where threats are supported by a much larger body of literature issues of scale, and the rapid pace of population changes, complicate application of available data at the regional or continental scale. Targeted research is needed to better understand these threats on a scale appropriate to species conservation.

1788 illustration of Trillium sessile by Sydenham Edwards. Originally published in The Botanical Magazine volume 2.

Methodology A variety of tools are available for evaluating extinction risk to plants. In North America, NatureServe’s global ranking system is the most widely used. Elsewhere in the world, the IUCN Red List’s method is more commonly used. These complementary species ranking methodologies were used to create conservation status assessments for North American Trillium species in 2019 and 2020, and were reviewed by an expert panel in a workshop at Mt. Cuba Center in October of 2019. The methodologies utilize the same underlying concepts and information, or “factors”, namely species’ rarity, threats, and population trends, however each evaluates the data differently. NatureServe’s method follows a weight-of-evidence approach, while the IUCN Red List’s method applies a series of rules, each with minimum criteria that must be met. NatureServe’s method places a greater emphasis on rarity, while trend data carry a stronger weight in the Red List methodology’s measure of extinction risk8. Figure 1 shows the comparable categories between the NatureServe and Red List extinction risk categories. Methods employed by both systems are briefly discussed below. For a detailed description of the thresholds used by NatureServe and the Red List, consult NatureServe Conservation Status Assessments: Methodology for Assigning Ranks9 and the IUCN Red List Categories and Criteria: version 3.110. Throughout this text, terminology borrowed from both organizations will be used. Subpopulations are defined according to the IUCN Red List’s definition of a group which exchanges fewer than one gamete per year with other groups. For Trillium, this is roughly synonymous with NatureServe’s definition for element occurrences indicating that a subpopulation occurs at least one km from another.

highly restricted ranges, it is of critical importance to consider the conservation status of these populations, even prior to a universally accepted taxonomic structure. Regardless of the direction taxonomic revision takes, efforts should be taken to maintain genetic diversity within accepted species and the morphological and genetic outliers presented here will remain of conservation concern. Currently accepted terminology is used where such terminology is not disputed. For species without validly published scientific names, but that are regionally recognized based on their distribution and habitat differences, variety numbers are used. These numbers were chosen to be consistent with Alan Weakley’s treatment of the genus14. Trillium pusillum var. 2 is notably missing as this variety has been subsequently elevated to the species level (Trillium georgianum) and is now broadly accepted.

Data Collection and Quality Control The best available information on all known, described species of North American Trillium species (and putative species) was first collated and used to develop distribution maps. Data were compiled using IUCN’s Species Information Service (SIS), a web-based database for storing and managing IUCN conservation assessments. Relying on data describing the species’ range, population, habitats, and ecology, uses, threats, current conservation measures, and other factors, conservation assessments were conducted following the IUCN Red List of Threatened Species Categories and Criteria version 3.110. Relevant data for assessments was gathered from a variety of sources including herbarium specimens, published and unpublished literature, Botanic Gardens Conservation International’s database of specimens15, national and regional floras, and consultation with numerous experts.

Taxonomy The taxa list for this evaluation was compiled by comparing Flora of North America11, NatureServe12, and the USDA PLANTS Database13. Considerable taxonomic uncertainty remains within the genus Trillium, and some species are recognized without having been uniformly accepted by authorities. Where such disagreements occur, attempts were made to assess species complexes as a whole, and under more narrowed taxonomic interpretations. The taxa presented here reflect a conservative approach based on the consensus of the 2019 Trillium Working Group. Taxa which have the potential to be elevated to the species level, even those which have not been validly published, were considered within Red List assessments for validly published species under which they are currently recognized. These are presented separately in this volume, not as a proposed revision of the taxonomy, but to ensure that revisions of the taxonomy can be rapidly accounted for in conservation assessments. As many of these proposed species have

Using this information, each species was assigned to one of the eight Red List conservation categories: Extinct (EX), Extinct in the Wild (EW), Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC), or Data Deficient (DD). CR, EN, and VU are considered “threatened” categories (Figure 1 and Appendix C). For further information on assessment methods, consult the IUCN Red List Categories and Criteria10 and the Guidelines for Using the IUCN Red List Categories and Criteria16. Conservation status assessments using NatureServe’s methodology which analyzes rarity, threats and trends9, 17 , were also conducted on all North American Trillium. NatureServe’s Conservation Status Ranks are nested in three 10

Figure 1: Comparison of NatureServe Ranks and IUCN Red List Categories.

Mapping

geographic scales: Global (G), National (N) and Subnational (S) (i.e. state and provincial). Subnational level data for all Trillium were gathered from NatureServe’s Network programs through a shared and distributed database, Biotics. These Subnational conservation status ranks and their related spatial data that detail the location, landscape condition and viability of each occurrence of the species in the jurisdiction, give a snapshot of the species’ extinction risk in each state or province. After the Subnational data were reviewed, primary and secondary literature were analyzed for data and information pertaining to species’ Global imperilment as outlined in Faber-Langendoen et al.9. The resulting Conservation Status Ranks Critically Imperiled (G1) to Secure (G5) (see Figure 1 for details). Conservation status ranks beginning with ‘T’ indicate a Global rank for a variety or subspecies, and should be preceded by the rank for the species, e.g. G4T1. In cases where there are multiple varieties or subspecies, the T ranks will sum to the species’ Global rank. Two additional global ranks, GX (Presumed Extinct) and GH (Possibly Extinct) are also used, and qualifiers “Q” and “C” are used when there is questionable taxonomy or when a species is presumed extinct but extant in cultivation, respectively.

Using ArcMap 10.3.118, taxa were mapped following the IUCN Mapping Standards and Data Quality guidelines19. It is critical to note that these guidelines are intended to incorporate the totality of a taxon’s natural range and maps may include large tracts of unsuitable habitat. Herbarium specimens and research grade observations from a variety of sources were used to inform the range polygons. Point data used to inform the polygon ranges presented in this volume are available for download along with the individual species assessments for each species at iucnredlist.org20. In addition to credible point data, published range maps were considered along with textual descriptions of species ranges. In some cases, the results follow biogeographic borders, in others, arbitrary lines following county or state boundaries are considered. The most up to date information was incorporated in each range map, and maps were subsequently reviewed and edited based on the authors’ expertise.

The resulting Red List and NatureServe assessments were reviewed by the Trillium Working Group 2019 at a workshop hosted by Mt. Cuba Center in October 2019. 11

Results and Evaluation Deficient. Criterion B (based on restricted geographic range of a taxon) was the most commonly used of the listing criteria (Table 3). Note that because multiple criteria may be used to list a species under a threatened category, the total number of taxa listed in all criteria is not consistent with the total number of threatened taxa.

The product of this effort is the first comprehensive conservation assessment of all North American species in the genus Trillium. Results of conservation assessments vary based on which taxonomic structure is considered valid. A comparison is made here between only those taxa which are validly published at the species level (Table 1, and Figure 2) and those that are considered by the authors to be most likely to be valid (Table 1, and Figure 3). Of the 53 North American Trillium taxa considered (using the narrowest taxonomic treatment for each taxon), 17 fall into a threatened category, 4 are listed as Near Threatened, and 27 are listed as Least Concern. Five taxa lacked sufficient information to assign to a category and are listed as Data

Results are similar for the accepted species, with slightly fewer taxa falling into threatened categories. The primary driver of this difference is the large number of taxa which could be listed as threatened within the Trillium ovatum and Trillium pusillum complexes.

Red List Category

Number of Taxa (Possible Future Taxonomy)

Number of Taxa (Accepted Species)

Extinct

Extinct in the Wild

Critically Endangered

Endangered

Vulnerable

Near Threatened

Least Concern

Data Deficient

Total

Table 1: Results of Red List assessment under different taxonomic interpretations.

NatureServe Rank

All Taxa

Accepted Species

Presumed Extinct

Possibly Extinct

Critically Imperiled

Imperiled

Vulnerable

Apparently Secure

Secure

Unranked

Total

Table 2: Results of NatureServe ranking at different taxonomic levels. The All Taxa column refers to the taxa with assessments in this booklet, some of which are provisional taxa. These taxa are indicated by a dagger symbol in the assessments. Accepted Species refers to those that are formally published and available on NatureServe Explore.

Figure 2: Number of taxa listed under each category using the broadest consideration of taxa within the genus Trillium.

Figure 3: Number of taxa listed under each category using the most likely taxonomic outcomes.

Red List Category

Number of Taxa

Percent of Threatened Taxa

76%

24%

Total

106%

Table 3: Number of threatened species listed under each IUCN Criterion following the most likely taxonomic structure.

Major Threats Clayton Meredith, New Mexico BioPark Society Trillium species in the southern United States, though the increasing spread of feral Pigs northward and westward suggests it is likely to become a threat to more species in the foreseeable future33. Damage caused by feral Pigs is especially concerning surrounding the Chesapeake Bay where several Trillium taxa with small ranges occur and where Pigs have not yet been reported but models suggest habitat is favorable33.

The most common threats to North American Trillium species are outlined in Figure 4. Threats were coded using the IUCN classification scheme16, 21. Invasive non-native species and problematic native species are a threat to the largest number of taxa regardless of their extinction risk. Of these threats, overabundance of White-tailed Deer (39 taxa threatened), and rooting by feral Pigs (34 taxa threatened) are the largest contributors. The threat posed by both species is very widespread and has been intensively studied 22–35 .

However, the impact of rooting feral Pigs is context specific and may impact habitats in disparate ways. Wetland habitats may benefit from disturbance caused by Pigs and may experience increased species richness following disturbance events35. Such benefits are likely to impact short-lived species rather than long-lived rhizomatous species like those in the genus Trillium. Upland areas, steep slopes, and areas with rocky substrates also provide some level of protection against disturbance caused by rooting. This leads to variation in the potential impact of Pigs on a taxonomic basis. In general, the sessile Trillium occur in lowlying areas and are less impacted by periodic disturbance. However, these areas are at greatest risk of substantial modification due to rooting activity and the sessile Trillium are generally considered to be subject to the greatest risk from feral Pigs.

The White-tailed Deer population in eastern portions of North America expanded dramatically through the 20th century, reaching densities that are greater than have occurred for thousands of years23. The causes of Whitetailed Deer overabundance are numerous, but significant factors include the widespread extirpation of large carnivores including Gray Wolves (Canis lupus) and Cougars (Puma concolor), reduced hunting pressure, and increased carrying capacities resulting from landscape alteration and fragmentation of forest habitats. Extensive documentation exists demonstrating Trillium population declines resulting from herbivory by White-tailed Deer. So well studied is this relationship, that T. grandiflorum and T. erectum are widely used as indicators of herbivory pressure22, 24, 25. The impact of White-tailed Deer predation varies according to characteristics of individual species with those that bloom earlier in the season, are taller, or have showy, sweetsmelling flowers being the most at risk of predation.

Both feral Pigs and overabundant White-tailed Deer compound the impacts of other invasive species and can contribute to broader habitat modifications which may result in reduced biodiversity34, 38, 39. Habitat modification can extend to the loss of favorable soil conditions through decreases in carbon to nitrogen ratios and loss of leaf litter34. The cumulative impact of disturbance caused by feral Pigs is likely to extend far beyond the immediate impacts causing direct mortality.

Management of White-tailed Deer populations and analysis of their impact is an extremely complex set of problems on an ecological, political, logistical, and social level. Monitoring must consider complex relationships between overabundant White-tailed Deer, and other processes. For example, the impacts of White-tailed Deer herbivory and collection of some species for horticultural or medicinal purposes has been demonstrated to have population impacts which are non-additive through the masking effect of browsing36. This is likely also the case for Trillium species which can undergo reversible stage class transitions, and should be a consideration when developing monitoring strategies. White-tailed Deer overabundance is an intractable longterm problem with few viable solutions and with impacts that are likely to persist long after White-tailed Deer populations are brought down to historic levels37. The political dynamics of managing increasingly fragmented habitats which lack apex predators are not likely to be solved in the foreseeable future, and the need for innovative solutions is dire.

Non-native competing plants also impact many Trillium species. Though Japanese Honeysuckle (Lonicera japonica) and Kudzu (Pueraria montana) are widely cited as major threats to Trillium species, it is unlikely that either species causes significant population declines. Kudzu may have paradoxically beneficial impacts for Trillium through the deterrence of White-tailed Deer, and through enriching soils with nitrogen while leafing out after most Trillium species have bloomed. The most impactful competing species, and those most likely to continue displacing Trillium species, are those that cause long-term habitat modifications and alter successional stages. Foremost among these are Chinese Privet (Ligustrum sinense), Bush Honeysuckle (Lonicera maackii), and Garlic Mustard (Alliaria petiolata), each of which forms dense stands which impede successional

Habitat disturbance caused by feral Pigs primarily threatens 14

Threats to western Trillium species differ dramatically from those in eastern North America. The taxonomy of western Trillium species is not well settled, and many of the taxa of greatest conservation need are recently described local or regional endemics, which are inherently susceptible to stochastic events and localized threats. Because of this, relatively low intensity threats may have disproportionately large impacts that are poorly understood relative to their eastern counterparts. The greatest threats to western Trillium species arise due to habitat modifications associated with logging, residential development, and alteration of natural fire regimes. In each case, these threats vary in intensity regionally. Logging poses serious threats to Trillium species in Oregon42, though these have declined in intensity in recent decades. Residential development is an acute threat surrounding rapidly expanding cities in the Puget Trough43, and the San Francisco Bay Area. Altered fire regimes are presently considered to be the most significant threat to western Trillium species and the negative impact caused by fire is expected to grow because of climate change in the region44. As with eastern species, competing invasive plant species may contribute to habitat quality declines. Himalayan Blackberry (Rubus armeniacus) is considered the most significant non-native competitor.

stages and directly impact herbaceous understory species. Burning Bush (Euonymus alatus), English Ivy (Hedera helix), Japanese Stiltgrass (Microstegium vimineum), Silverberry (Elaeagnus commutata), Trifoliate Orange (Poncirus trifoliata), and Winter Creeper (Euonymus fortunei) are among the other non-native plants which compete with or exclude Trillium species. An invasive insect, the Hemlock Woody Adelgid (Adelges tsugae), threatens two species as it can impact the forest composition upon which the species are dependent. Other threats include habitat loss due to development for residential or commercial purposes, silvicultural practices, and mining. Much of the genus’ diversity is concentrated in the southeastern United States, a region projected to experience extremely rapid expansion of urban areas into adjacent forested areas in the coming decades40. Collection for medicinal and horticultural purposes is a poorly documented threat which may have significant impacts on several species. Medicinal collections are geographically focused in the Appalachian Mountains and impacts to species in this area are expected to be locally severe41. Horticultural collections are expected to be most severe for rare species which are intrinsically susceptible to population declines and more highly valued on horticultural markets.

Figure 4: Number of taxa impacted by threats as categorized according to the IUCN-CMP Unified Classification of Direct Threats21.

The Trillium Collections at Mt. Cuba Center Amy Highland, Mt. Cuba Center Trillium experts from across the United States gathered together at Mt. Cuba Center in Hockessin, Delaware in October 2019. We all mused on the irony of being in a beautiful garden while storms trapped us indoors. We took advantage of the unprecedented gathering of botanical knowledge to assess the current state of the genus in the wild. In those rainy days, we saw the beauty and value of Mt. Cuba Center’s Trillium Collections in a way most visitors cannot. The phenotypes, metadata, history, the commitment to the genus were all recognized as critically important. As we talked through each species, the conversation gradually turned from one of loss and destruction, to one of future needs and action. Actions such as the continued development of ex situ collections in conservation gardens around the world.

and a source of restoration materials. While also inspiring and motivating visitors to care about nature and the world around us through stunning Trillium displays. Mt. Cuba Center’s commitment to Trillium continues today and we are happy to join our partners to develop these vital species assessments. Truly great collections, built over time, tell us a good deal about ourselves and what we value. In these last few decades, botanical gardens have seen a shift in our living collections to include more plants of conservation concern, more plants native to the environments from which they came, and more interest in understanding the interactions among living things. We are delighted to witness this time of conservation action perpetuated by our gardens and the efforts of the Trillium Working Group.

The Trillium Collection at Mt. Cuba Center began in the 1960s with the diminutive Trillium nivale. Our founder, Mrs. Pamela Copeland, was passionate about this uncommon wildflower and worked with Mt. Cuba’s fi rst director, Dr. Richard Lighty, to lay the foundations of our research ambitions. Repeated generations of leaders at Mt. Cuba Center have committed to this genus, creating a renowned and stately collection. In nearly 60 years of stewardship, the collection has grown to comprise 90 taxa represented by 463 accessions, including intrageneric hybrids, celebrated cultivars, and rare color forms. Wild documented mother lines round out the collection with much needed data and distinct genetic variability. Over the years, prominent accessions were donated by Fred and Roberta Case, who authored the authoritative volume, Trillium, and named the beautiful double-form Trillium grandiflorum ‘Pamela Copeland’ for our founder, as a testament to their connection and mutual respect. Other notable additions originated from Louise Smith’s Alabama home, and showcase the variation in the mottled, silver foliage of many sessile Trillium. These early partnerships not only added depth and interest to our Trillium collection, they demonstrated the ability of the collection to bring people together and create communities. Working with our partners in conservation and horticulture, we bring together a collection of forms and ecotypes; turning our inspiring gardens into a living laboratory and productive seed bank.Threats and environmental demands are converging to push these valuable plants into decline in the wild. Mt. Cuba Center acts as an ark, an observer,

Trillium flexipes x erectum photograph by Shelly Silva, courtesy of Mt. Cuba Center

A note on the taxonomy of Trillium Edward Schilling, University of Tennessee Aaron Floden, Missouri Botanical Garden Wesley Knapp, NC Natural Heritage Program, NatureServe have not been formally named are the “Ovatum Group” and the “Grandiflorum Group”.

Trillium includes about 60 species and is part of a group that was traditionally assigned to Liliaceae, recognized as its own distinct family, or most recently considered to be tribe Parideae of Melanthiaceae. This last placement, based on results from molecular phylogenetic studies, was unanticipated from earlier morphologically based classifications. Tribe Parideae, with over 90 species, represents a huge increase in diversity relative to its most closely related tribes, Xerophylleae (2 species), Chionographideae (8 species) and Heloniadeae (9 species). A major change in Parideae relative to the rest of the family is having a single flower with prolonged anthesis rather than a dense inflorescence of individually small, short-lived floral units. The tribe is also distinctive in having huge genomes, with Kinugasasō (Paris japonica) having the largest yet documented for a flowering plant species.

The sessile-flowered group of Trillium, subgenus Sessilium, is well circumscribed by the lack of a flower pedicel above the bracts, and by the presence of mottling on the leaves. This group now includes over 25 species, including 3 species newly described in the last 12 years. The center of diversity for this group is in the southeastern U.S., but there is a secondary center in western North America where 5 species occur. Undescribed species may be presented in both geographic areas. The sessile-flowered Trillium are notable for the broad range of variation in floral scent, ranging from sweet lemony odors to quite repugnant carrion and excrement types. The chemical composition and ecological significance of these odors is an area of active investigation.

There is not yet unanimous opinion on the generic boundaries of Trillium45. Molecular phylogenetic studies have identified a species from western North America with a Trillium-like appearance as a clearly distinctive entity, and it is now classified as Pseudotrillium rivale. Molecular data also suggest that the beautiful and distinctive Painted Trillium should be classified, together with a Himalayan species, in a distinct genus Trillidium, although the separation of these from Trillium is not universally accepted46. The other genus in the tribe, Paris, is viewed variously as a single genus, or as a lineage that includes two other genera, Daiswa and Kinugasa. Paris, Daiswa, and Kinugasa are distinctive in having 4- to 11- merous flowers, compared to the trimerous flowers of Trillium, and the distribution of the Paris lineage is restricted to Asia and Europe46.

The sister group to the sessile Trillium appears to be subgenus Delostylium. The subgenus is distinctive in having the bases of the three stigmas united into a slender style above the ovary. About 12 distinct entities have been noted in this subgenus, although not all have been formally named. One of the rarest species of Trillium, T. persistens (Edna’s Trillium) is part of this subgenus and is listed as Endangered under the United States Endangered Species Act. The “Erectum Group” includes species in North America that are closely related to Trillium erectum and all the Asiatic species of Trillium. This group is distinct in having short, stout stigmas that are recurved at the tip. The specieslevel taxonomy is incompletely resolved, particularly in North America. Unpublished dissertation studies based on isozymes and molecular markers have failed to find distinct boundaries between many of the species, and interspecific hybridization may be a factor. In Asia all but one of the species are polyploids, and interspecific hybridization has been documented.

The outlook on the infrageneric classification of Trillium has changed substantially with the availability of molecular phylogenetic data. The traditional view was a split between two subgenera, with the sessile-flowered species forming subgenus Sessilium (earlier called subgenus Phyllantherum), and the pedicellate-flowered species making up subgenus Trillium. Molecular data confirm the monophyly of subgenus Sessillium but show that subgenus Trillium is a paraphyletic group composed of several distinct lineages. Of these, only subgenus Delostylium has been named and formally circumscribed47. The lineage that is sometimes referred to as the “Erectum Group” includes the type species of the genus, T. cernuum, and thus is automatically called subgenus Trillium. Two other lineages that appear to be distinctive but

The “Ovatum Group” consists of a complex of closely related taxa that occur in western North America. Trillium ovatum was once thought of a single species, but molecular data suggest that at least four different species are now embraced under this name. The diminutive Trillium hibbersonii from Vancouver Island in Canada has recently been recognized as distinct from T. ovatum and shown to be part of the “Erectum Group”. Trillium crassifolium also is 17

distinct from the “Ovatum Group” and is instead part of the “Grandiflorum Group”, with some sources recognizing it as a distinct species. The “Grandiflorum Group” includes at least two common species of North America, T. grandiflorum and T. nivale. These species are quite distinctive, with plants of T. grandiflorum large, robust, and midseason bloomers, whereas those of T. nivale are small, dainty, and among the earliest of the spring ephemerals to bloom. Trillium exhibits a classical pattern of geographic distribution that was once termed Arcto-Tertiary, with centers of distribution in eastern and western North America and in eastern Asia. The area with the largest number of species is the southeastern United States. The number of species in western North America is far fewer, but the phylogenetic diversity in this area rivals that of eastern North America. In contrast, eastern Asia has many fewer species, and all of them belong to the same infrageneric lineage, the “Erectum Group”. Ongoing studies suggest that the disjunction among geographic areas was achieved not in a single event, but rather through multiple movements of different phylogenetic lineages within the genus. Use of molecular genetic markers has helped to solidify Trillium taxonomy and aid in conservation assessments. This is needed because of the overall similar appearance of all Trillium, and the tendency for teratogenic forms (such as having doubled flowers or atypical numbers of floral parts) to occur in many species. Use of genetic markers led to recognition of Trillium delicatum, and to clarification of the distinctiveness of T. hibbersonii, both of which are rare and in need of protection. Conversely, molecular markers show that Trillium ovatum var. maculosum is merely a local form of typical T. ovatum with oddly spotted leaves which is not genetically different from it. Future studies are still needed to clarify the taxonomy of the “Ovatum Group”, which may include one or more rare species of conservation concern that are not currently recognized.

William Jackson Hooker’s 1830 illustration depicting Trillidium undulatum.

On western Trillium Kjirsten A. Wayman, Humboldt State University While western Trillium do not have the significant cultural and medicinal history that eastern Trillium have, they are revered by plant enthusiasts and the public for their undeniable beauty. Depending on the species and the localities where they occur, western Trillium begin blooming in mid-winter or early spring as some of the first flowers of the year, adding to their attraction.

been observed in and around the flowers, it is still unclear whether beetles are the pollinators, whether self-pollination is sufficient, or if another mechanism is operating. Hybridization and introgression of the western sessile Trillium also appear to be occurring in various regions of the Pacific west, seen in the intermediate morphology of select populations.

In western North America there are anywhere from six to ten recognized species of Trillium, a few of which have noted varieties or subspecies. Of these, five are sessile (the flower is stalk-less) and one species complex is pedicellate (the flower is born on a stalk).

The main threats to Trillium populations in the west are the loss of habitat due to wildfire or encroaching development. It is still unclear how severe the effect of wildfire is, or will be, on Trillium populations. The Trillium plants themselves can easily survive a wildfire as their rhizomes are well underground and the above ground foliage has usually died back before the arrival of fire season. However, the changing vegetation and increase in low growing shrubs and herbaceous plants after a fire may decrease the survival of existing Trillium plants and recruitment of seedlings.

Trillium ovatum, the pedicellate species complex, shows widely varying morphology across its range. There are up to 5 taxa within this complex, one of which, T. hibbersonii, was recently determined to be distinct from T. ovatum. Future research will provide greater clarity on whether the other recognized taxa in this complex, T. crassifolium, T. ovatum subsp. oettingeri, and T. scouleri, are justified as distinct species from T. ovatum subsp. ovatum. The five species of currently recognized western sessile Trillium are T. albidum (subsp. albidum and subsp. parviflorum), T. angustipetalum, T. chloropetalum (var. chloropetalum and var. giganteum), T. kurabayashii, and T. petiolatum. Some treatments elevate T. albidum subsp. parviflorum to the species level, and other treatments combine T. kurabayashii with T. angustipetalum. There is also taxonomic uncertainty regarding the varieties of T. chloropetalum. While T. petiolatum is very distinct, the other four sessile-flowered species have many overlapping traits among them and significant infraspecific variability, making species boundaries difficult to define and identifications troublesome in many cases. These variable traits include petal color, petal shape, stamen to ovary ratio, ovary color, stamen color, mode of anther dehiscence, among others. Molecular data published to date have been unable to resolve these species, likely due to their more recent divergence in evolutionary history. Owing to their great variety of petal colors and shapes, the interesting mottling patterns on their leaves, and pleasing or curious floral scents, Trillium enthusiasts are drawn to these plants and search far and wide to discover the full extent of their variation. The mystery of their taxonomy remains unsolved; however, a bit of clarity is gained with each research study that is pursued. In addition to the taxonomy, the insects that may be responsible for pollination of the western sessile Trillium species are also a mystery. While many tiny beetles have 19

Floral scent, taxonomy, and ecology of Trillium in North America Kjirsten A. Wayman, Humboldt State University Robert A. Raguso, Cornell University O

Many people are surprised to learn that Trillium flowers often are strongly and distinctively scented. This may reflect that Trillium flower close to the forest floor where they are rarely sniffed, or that their fragrances dissipate in the open, breezy landscapes in which they bloom. Perhaps people are simply charmed by their colorful displays. Nevertheless, most Trillium flowers are scented in ways that provide information about their taxonomic and ecological relationships.

isobutyl acetate (banana)

O CH 3O

Floral scent is another character, like petal color, petal shape or petal number, that can be used to describe a plant. While floral scent cannot be as easily or reliably described based on human perception, its chemical composition can be analyzed. The floral scent in Trillium, mainly originating from the petals, is composed of volatile organic compounds that can be absorbed onto a substrate and subsequently injected into a gas chromatograph – mass spectrometer for chemical analysis. Morphological characters are generally used to identify a particular taxon, and floral scent composition can similarly be used in Trillium as a key identifying trait.

eugenol (clove)

HO H O O

Floral scents usually represent blends of volatile organic compounds produced by different biosynthetic pathways. Scent blends can be simple (3-5 related compounds in petunias) or complex (over 100 diverse compounds in the common sunflower). Esters, ketones, alcohols, monoterpene and sesquiterpene hydrocarbons, oxygenated terpenes, benzenoid compounds and organosulfur compounds are the dominant types of volatiles found in Trillium floral scents (Fig 5). Some compounds are present across multiple species, while others are unique to a particular taxon or found only in a few species. Generally, however, the set of compounds and the ratio in which they occur is unique to a given species (including any variation that may also exist). For example, candy-sweet smelling 6-methyl-5-hepten-2-one (also known as sulcatone) is found in significant quantities in T. kurabayashii, whereas it is sometimes a minor compound in T. albidum or T. chloropetalum and is never found in T. angustipetalum (Wayman, unpublished results, Fig 6).

geranial (lemon) sulcatone (fruity)

Figure 5: Representative examples of compounds in Trillium species.

Thus, floral scent composition can be thought of as a signature of a particular species. Although there may be variation within a species and among populations, the set of compounds characteristic of a species or population generally remains consistent. In this way, the floral scent composition can behave as a species marker. When Victor Soukup25 discovered T. parviflorum (currently T. albidum subsp. parviflorum) in the Pacific Northwest, he described the flowers as having a distinctive “clove-like” scent, which he felt was a unique trait to T. parviflorum, distinguishing it from the closely related T. albidum. Subsequent research has identified eugenol as the chemical source of the clove-like scent in T. parviflorum. However, discovering its presence in a few northwestern populations of T. albidum revealed that eugenol is not unique to T. parviflorum (Wayman, unpublished results). In this case, a shared floral scent trait challenges us to reassess our species concept for T. albidum and consider whether currently isolated northwestern populations are relicts of a historically broader and less fragmented distribution.

of many Trillium are individual volatile compounds with distinctive ecological roles. For example, dimethyl disulfide lends a sharp, fetid odor to the unusual maroon flowers of T. petiolatum. This compound is universally present in flowers that mimic carrion, including some of the world’s largest and strangest flowers (Dead Horse Arum, Rafflesia, Stapelia and Aristolochia), all of which are pollinated by Blowflies (Calliphoridae)36. Interestingly, dimethyl disulfide is produced by several red-flowered, sessile Trillium species native to southeastern USA that are not each other’s closest relatives, suggesting independent origins of carrion mimicry in the genus. Other Trillium with similar red, sessile flowers produce volatiles indicative of ripe fruit (isobutyl acetate), yeast (acetoin) or dung (p-cresol). From an ecological standpoint, these findings predict that different kinds of pollinators (e.g., sap beetles, fruit flies and dung flies or beetles, respectively) should be attracted to these Trillium species, perhaps as a mechanism to reduce competition for pollinators. From an evolutionary standpoint, such findings suggest that pollination systems have diversified through chemical mimicry of different kinds of decaying substrates in the genus Trillium.

Embedded within the species-specific floral scent blends

Figure 6: A heat map showing relative percentages of compounds in the total floral scent of 4 individuals from a single population of each species. Taxa include T. albidum, T. angustipetalum, T. chloropetalum, and T. kurabayashii. Numbers 1-16 represent individual compounds.

History of Medicinal Use Susan Leopold, United Plant Savers Trillium have a rich history in medicinal use in the United States but also in China, India, Pakistan and other regions around the world where they grow. The bioactive components of Trillium, steroidal saponins, are contained in their roots48. Trillium are known to be astringent, tonic, and antiseptic49. This makes for wide application in Trillium being used as an ingredient in herbal formulas as well as being used as a single tincture. Its common names, ‘Birth Root’ or ‘Beth Root’, reflect a history of being used for women during and after birth and for preventing and mitigating hemorrhages50. The history of side income derived from trapping for the fur trade as well as digging roots and harvesting barks for the medicinal plant trade dates back to 1700s in rural Appalachia. Much of the plant knowledge and formulation of herbal products is based on folk knowledge that has been passed down over generations, much of it derived initially from Indigenous practitioners51. The demand for herbal products in the United States hit a peak during the late 1800’s and early 1900’s when there were many schools of eclectic medicine that promoted the use of plant-based remedies. It was common in this period for small store to purchase a plethora of herb-based medicines. This all changed with increasing dominance of allopathic trained doctors and the development and use of synthetically produced derived medicines51.

permit may be required for digging plants but the process varies across Forests, and in most cases plants on private lands can be collected without state or federal permits. Social media has become a place where thousands of root diggers and buyers connect, as well as offering visual evidence of the toll taken on native plant populations. In a volunteer survey of American Ginseng (Panax quinquefolius) dealers in a few southern states, the Department of Forest Resources and Environmental Conservation at Virginia Tech reported that between 2013–2016, 1,338 pounds of Trillium were purchased at an average price of $3.11 per pound41. It is important to note that the number of dealers surveyed was a fraction that purchased in those years, and with approximately 200 dried Trillium rhizomes making a pound, the number of plants removed from the wild is in the hundreds of thousands. What’s more, this data point represents wild collection for the medicinal plant trade only, and it is widely known that these plants are sold as ornamental plants by nurseries. Even though native plant regional societies and native plant nurseries have clear guidelines, Trillium are a highly sought-after plant in the nursery trade for its beautiful flowers and fondness as a spring ephemeral. Individual plants sell anywhere from 5 to 15 dollars, with rarer varieties commanding even higher prices. The nursery trade in Trillium is also difficult to study due to its highly dispersed nature, and a lack of supply chain monitoring. There is a huge discrepancy is the value of Trillium as a living plant in the nursery trade and the value of the dried root for the medicinal plant trade. How can 100 plants be valued at 1 to 3 dollars when sold on herbal markets while the same plants could command 500 dollars in horticultural markets? In part, this can be attributed to lack of understanding of the dealers and brokers involved in horticultural trade. Markups prior to entering horticultural markets are likely, and it’s unclear how prices paid to diggers vary. In conversations with dealers, they lament that it is difficult to find diggers who have harvested and dried Trillium when they can sell a single rhizome fresh for a higher price to those looking to repot and sell into the nursey plant trade. In personal comments from a digger, the dealer told the digger that if she didn’t dig Trillium in the spring then the dealer would not buy the digger’s much more lucrative American Ginseng harvest in the fall.

Currently we are witnessing a renaissance in the demand for plant-based products that are now regulated under the Dietary Supplement Act passed in 1994. The legislation provides some regulation for herbal products but clearly states that no medical claims can be made on herbal products52. This regulation, however, has created challenges on how products are marketed and formulated because while there are guidelines on processing plants, sourcing and purity standards are lacking. Companies are required to document some form of tracking the plants in the supply chain, but current techniques are unable to properly identify similar species and a company is only held accountable if they are audited by the FDA53. Plants that are used in the making of pharmaceutical grade drugs have to comply with much stricter conservation protocols but for those regulated by the Dietary Supplement Act, requirements on sustainability do not apply.

Information on the trade While there are international laws regulating trade of medicinal plants, trade within the United States is largely unregulated and quantifying the magnitude of trade is difficult. On public lands, such as National Forests, a 22

Ending the Trillium Trade in Commercial Herbal Products United Plant Savers, a non-profit founded in 1994 dedicated to native medicinal plant conservation, lists Trillium on its At-Risk list. There are several common species that are abundant and easy to cultivate that provide accessible analogues for the traditional uses of Trillium. Mother Wort (Leonurus cardiaca) is purported to be an effective uterine tonic. Yarrow (Achillea millifolium) is often stated to be very effective as an anti-hemorrhage herb as is Shepherd’s Purse (Capsella bursa-pastoris), which is also purported to be effective as an astringent. Raspberry leaf (Rhus idaeus) is used commonly used to tonify the reproductive system. United Plant Savers supports the work of those who are dedicated to cultivating Trillium for the horticulture trade and for conservation purposes. Without any efforts to use cultivated sources of Trillium for the commercial trade in herbal products compounded by the fragility of such a slow growing woodland spring ephemeral, United Plant Savers advocates for the ending of the Trillium trade in commercial herbal products.

Illustration of Trillium erectum by Charles Millspaugh. This image is included in his 1887 volume American Medicinal Plants: An Illustrated and Descriptive Guide to the American Plants Used as Homeopathic Remedies.

Species Assessments The following pages contain individual assessments for Trillium taxa assessed by both NatureServe and the IUCN Red List. Accounts include relevant data that support each taxon’s conservation status and a map of the taxon’s range. Maps incorporate information on the origin and presence of taxa in each area. Species accounts are structured as follows:

Binomial name Authority Pedicellate or Sessile Red List Category & Criteria NatureServe Global Rank CA: Canadian provinces where taxon occurs US: States where taxon occurs

Figure: 7 Key to presence and origin designations in maps.

Narrative justification Red List Assessor(s) NatureServe Global Rank Reviewer(s) References

States and provinces may also include qualifiers providing additional information about occurrences in these areas as follows: H

Historical occurrences which may or may not persist at present

Introduced

Origin uncertain

Pseudotrillium rivale

Trillidium undulatum

(S.Watson) S.B. Farmer

(Willd.) Floden & E.E. Schilling

Pedicellate Vulnerable B1ab(iv) US: CA, OR

Pedicellate Least Concern* Secure (G5) CA: NB, NS, ON, PE, QC US: CT, GA, KY, MA, MD, ME, MI, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VA, VT, WV

Vulnerable (G3)

Painted Trillium (Trillidium undulatum) is broadly distributed from Ontario, Quebec, and Nova Scotia south through the Appalachian Mountains to Georgia. It occurs in a variety of habitats and forest communities, and requires cool acidic soils. In the southern part of its range, it only occurs at elevations greater than 600 meters. The species’ population is not well understood and additional research is needed to determine the population trend. It is threatened by herbivory pressure associated with an overabundance of White-tailed Deer, habitat degradation caused by feral Pigs, and soil acidification caused by air pollution. Though the population trend is not well understood, given the species’ broad range there is a very low risk of extinction.

Brook Wakerobin (Pseudotrillium rivale) occurs in the Klamath and Siskiyou Mountains of northwestern California from northern Humboldt County, western portions of Siskiyou County and throughout Del Norte County, north to Coos, Curry, Jackson, and Josephine Counties, in Oregon. It is locally common on moist serpentine soils in association with open yellow-pine forests, manzanita chaparral, clearings in sequoia groves, riparian areas, Darlingtonia bogs, and gravelly roadsides. The species is threatened by disruptions to natural fire regimes that have resulted in heavy accumulated fuel loads. The 2002 Biscuit fire burned the entire species’ range, likely resulting in decreased habitat quality. The species may also be threatened by Elk (Cervus canadensis) predation, invasive plants, and logging. Most of the species’ range falls within the Rouge RiverSiskiyou National Forest, but existing protections may not adequately address threats.

*The Red List includes Trillidium synonym of Trillium undulatum Willd.

undulatum

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

Red List Assessor(s): Wayman, K.A., Meredith, C.R. & Trillium Working Group 2019

NatureServe Global Rank Reviewer(s): Treher, A. NatureServe Global Rank Reviewer(s): Wayman, K.A. & Oliver, L.

Refs: 1, 11, 13, 24, 25, 48, 49, 54, 55, 57, 59, 69–74, 76–85

Refs: 1, 11, 13, 15, 42, 48, 49, 54–76

Trillium albidum

Trillium albidum subsp. albidum

J.D.Freeman

Sessile N/A Apparently Secure (G4G5) US: CA, OR, WA

Sessile Least Concern* US: CA, OR

Apparently Secure (T4T5)

The taxonomic status and rank of Trillium albidum, and its infraspecies, are unclear, and in recent treatments members of the species complex have been recognized at both the species and subspecies levels. They are treated here in a strict sense, with NatureServe recognizing two taxa at the subspecies level. The Red List includes both taxa at the species level. However, the species concepts employed in both frameworks are synonymous. Considered in the broad sense, both authorities agree that the risk of extinction for the species complex is low.

Refs: 1, 11, 48, 49, 57, 69, 71–74, 76, 83, 84, 86, 87

Giant White Wakerobin (Trillium albidum subsp. albidum) occurs in mountainous areas, extending from Monterey County, California north along the Coast Range to Columbia County, Oregon as well as in the Cascade, Klamath, and Sierra Nevada Mountains. It occurs in various habitats including redwood forest edges, mixed deciduousconiferous forests, coastal scrub, chaparral, moist canyon slopes, and riparian areas. Extensive hybridization occurs with T. albidum subsp. parviflorum in northern parts of its range, and with T. chloropetalum in the San Francisco Bay Area. Wildfire, urban development, and invasive plants could impact some subpopulations; however, it is relatively tolerant of disturbance. This taxon is at low risk of extinction due to its relatively large population, extensive range, and absence of specific threats. *The Red List includes Trillium albidum subsp. albidum as a synonym of Trillium albidum J.D. Freeman

Red List Assessor(s): Wayman, K.A., Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Wayman, K.A. & Oliver, L. Refs: 1, 11–13, 15, 42, 48, 49, 54, 56, 57, 67, 69, 71–74, 76, 83, 84, 86–90

Trillium albidum subsp. parviflorum

Trillium angustipetalum

(V.G. Soukup) K.L. Chambers & S.C. Meyers

(Torr.) J.D.Freeman

Sessile Vulnerable C2a(i)* US: OR, WA

Sessile Data Deficient US: CA

Imperiled (T2T3)

Smallflower Trillium (Trillium albidum subsp. parviflorum) is endemic to the Puget Trough ecoregion of northwestern Oregon and southwestern Washington. The species occurs in oak and hardwood communities and wetland habitats, which are increasingly threatened by development within the region. Other threats include changes to hydrology, competing invasive plants, and timber harvest. Conservation efforts for the species should be focused on protecting and maintaining adequate amounts of suitable habitat. The population is small and thought to be in decline. Just over 5,000 plants occur in Washington and probably fewer than 1,000 in Oregon. The largest known subpopulation, located on the Fort Lewis Military Reservation, is under 1,000 individual plants. Due to its limited, declining population, the taxon is considered at moderate to high risk of extinction.

Apparently Secure (G4)

Narrowpetal Wakerobin (Trillium angustipetalum) occurs in the Sierra Nevada Range of California from Fresno County to Yuba County. Disjunct subpopulations also occur in Santa Barbara and San Luis Obispo Counties. It is noted to be uncommon, and occurs in montane areas including mixed conifer forests, relatively moist woodland foothills, and riparian areas. It is found in association with sequoia in the Sierra Nevada, and with maples, and oak groves in riparian areas extending into chaparral habitats at lower elevations. There are few documented threats to this species, although Himalayan blackberry is likely to present some level of competition, which may be facilitated by fire risk in the species’ habitat. It is known to occur in several protected areas including Montaña de Oro State Park, in San Luis Obispo County, and Yosemite National Park. Due to the lack of information on population size and trend, as well as specific threats, this species is listed as Data Deficient on the Red List. NatureServe considers the species as Apparently Secure; however, if the disjunct subpopulations are excluded, the species’ Global Rank would be more imperiled.

*The Red List includes Trillium albidum subsp. parviflorum as a synonym of Trillium parviflorum V.G.Soukup

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 Red List Assessor(s): Wayman, K.A., Meredith, C.R. & Trillium Working Group 2019

NatureServe Global Rank Reviewer(s): Oliver, L. & Wayman, K.A.

NatureServe Global Rank Reviewer(s): Wayman, K.A. & Oliver, L.

Refs: 1, 11–13, 43, 48, 49, 54, 56, 59, 61, 71–74, 76, 83, 84, 86–88, 91–100

Refs: 1, 11, 15, 48, 49, 54, 55, 57, 66, 67, 69, 71–74, 76, 83, 84, 86, 101–106

Trillium catesbaei

Trillium cernuum

Elliott

Pedicellate Least Concern US: AL, GA, NC, SC, TN

Pedicellate Least Concern Secure (G5) CA: MB, NB, NL, NS, ON, PE, QB, SK US: CT, DE, DC, IL, INH, ME, MD, MA, MI, MN, NH, NJ, NY, ND, OH, PA, RI, SD, VT, VA, WV, WI

Apparently Secure (G4G5)

Bashful Wakerobin (Trillium catesbaei) occurs in the southern Piedmont region from North Carolina south to Alabama. The species is also present in the Tennessee Valley in Tennessee, Georgia, and Alabama, as well as portions of the Gulf Coast Plain in southern Alabama, and rarely on the Coastal Plain of North Carolina. Within this range, it occurs on acidic soils in cove forests, laurel and rhododendron thickets, and open dry woodlands. It often occurs in areas where habitats are unsuitable for other Trillium species but has a somewhat unpredictable distribution and a highly variable population density. The species is commercially available as an ornamental, but the market for the species is quite small. The primary threat to this species is herbivory from an overabundance of White-tailed Deer within its range. The species occurs in several protected areas including the Great Smoky Mountains National Park, but most of the species’ range is not protected. Given the species’ wide range and large population, it is at low risk of extinction.

Nodding Trillium (Trillium cernuum) occurs across a broad range in northeastern North America from Saskatchewan, east to the Canadian maritime provinces, and as far south as northern Virginia. Though population declines have been noted, the species is quite abundant, especially in Michigan. It occurs in deciduous forests in its southern distribution, and extends into coniferous forests within its northern range. It is commonly found in wetland areas. Historically, habitat loss was this species’ greatest threat; however, herbivory from an overabundance of White-tailed Deer is currently the primary threat. Competition with introduced Garlic Mustard also impacts some subpopulations. Despite its listing as Endangered by the states of Illinois and Indiana, and some indications of population decline in other places, the species is widespread and relatively common.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

NatureServe Global Rank Reviewer(s): Treher, A.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

Refs: 1, 11, 13, 15, 24, 25, 29, 32, 48, 49, 54, 55, 57, 59, 69, 71–74, 76, 81, 83, 84, 86, 108, 110, 113–118

NatureServe Global Rank Reviewer(s): Treher, A. & Frances, A. Refs: 1, 2, 11, 13, 15, 25, 26, 29, 32, 48, 49, 54, 55, 57, 69, 71–74, 76, 81, 83–86, 91–93, 102, 106–112

Trillium chloropetalum

Trillium cuneatum

(Torr.) Howell

Raf.

Sessile Data Deficient US: CA

Sessile Least Concern Apparently Secure (G4G5) US: AL, GA, ILI, KY, MDI, MII, MS, NC, PAI, SC, TN, VAU

Apparently Secure (G4)

Giant Trillium (Trillium chloropetalum) is a California endemic found generally in the Greater San Francisco Bay Area from northern Monterey County to southern Mendocino County. The species’ population trend is unknown, but it is often abundant in city parks and gardens. Ethnographic accounts document use of the plant as an analgesic and as a burn dressing among the Costanoan, and Yurok tribes, respectively. It is one of the most widely cultivated species of Trillium in the horticultural trade. Wild collection is thought to supply a substantial portion of this market. Urban growth may present some threat to the species, though it is tolerant of small patches of habitat in parks and open spaces. Wildfire may also be a threat to this species. There is taxonomic uncertainty within the species, and some sources recognize material considered here as variety giganteum (Hook. & Arn.) Munz at the species level. Due to the taxonomic uncertainty, this species is listed as Data Deficient by the Red List. Should two distinct species become formally recognized, the species elevated from var. chloropetalum would likely be listed in a threatened category. Trillium chloropetalum, including the material that would be assigned to giganteum, is considered to be at low risk of extinction by both the Red List and NatureServe.

Cuneate Trillium (Trillium cuneatum) occurs from central North Carolina and southern Kentucky to Georgia and Mississippi. The species is known to have escaped cultivation in Michigan and may also have been introduced to Illinois, Maryland, Pennsylvania, and Virginia. In favorable habitats, the species may be a common component of understory communities. It occurs in upland woods and disturbed areas including mine tailings, ditches, and old fields. Several cultivars of this species are available commercially. The impact of horticultural trade on the wild population is unknown. An overabundance of White-tailed Deer and competition with invasive plants, specifically, Bush Honeysuckle and Chinese Privet, are the most significant threats to the species. Additional research is needed to determine the population trajectory for the species. Due to its wide range and large population, the species is not considered to be at risk of extinction.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Frances, A. Refs: 1, 2, 11, 13, 15, 32, 48, 49, 54, 55, 57, 59, 64, 69, 71-74, 76, 81, 83, 84, 86, 108, 113, 122-125

Red List Assessor(s): Wayman, K.A., Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Oliver, L. & Wayman, K.A. Refs: 1, 11, 13, 48, 49, 54–57, 59, 61, 64, 67, 69, 71–74, 76, 83, 86, 101, 110, 119–121

Trillium decipiens

Trillium decumbens

J.D.Freeman

Harb.

Sessile Least Concern US: AL, FL, GA

Sessile Least Concern US: AL, GA, TN

Vulnerable (G3G4)

Deceiving Trillium (Trillium decipiens) is distributed within the Gulf Coast Plain of western Florida, southern Alabama, and portions of Georgia. It occurs on a variety of soil types but is most common on sandy calcareous substrates within mixed deciduous communities and upland oak woods. Logging and silviculture present the most substantial threats to this species. Other threats include herbivory by the overabundance of White-tailed Deer, invasive plants including Silverberry and Chinese Privet, rooting by feral Pigs, and infection from an unknown fungal species that inhibits reproduction. Despite the presence of threats to the species, it is considered to be at low to moderate risk of extinction.

Apparently Secure (G4)

Decumbent Trillium (Trillium decumbens) occurs in the Ridge and Valley, and the Cumberland Plateau physiographic provinces of Alabama, Georgia, and Tennessee. It is reported to be locally abundant throughout its range occurring in densely wooded areas on rocky substrates and riparian areas. In addition, it is collected as an ornamental, and may be threatened by logging. Mining, damage caused by feral Pigs, and herbivory associated with an overabundance of White-tailed Deer also threaten the species. Since threats to the species are currently low in intensity and unlikely to result in serious population declines, it is not considered to be at significant risk of extinction. Additional research is needed to determine the suitability of remediated mines as habitat for the species and the effectiveness of different remediation methods. Population monitoring is warranted given the nature of the threats to the species and its limited range.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Treher, A.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

Refs: 1, 11, 12, 14, 15, 25, 31, 48, 49, 54, 55, 57, 59, 69, 71–74, 76, 81, 83–86, 101, 108, 109, 113, 126–128

NatureServe Global Rank Reviewer(s): Treher, A. & Frances. A. Refs: 1, 11–13, 48, 49, 54, 55, 57, 59, 69, 71–74, 76, 77, 83, 84, 86, 101, 108, 117, 124, 129–131

Trillium delicatum

Trillium discolor

A.Floden & E.E.Schill.

T. Wray ex Hook.

Sessile Endangered B1ab(iii,v) US: GA

Sessile Near Threatened US: GA, NC, SC

Critically Imperiled (G1)

Vulnerable (G3)

Ocmulgee Trillium (Trillium delicatum) is known from four scattered subpopulations in the Ocmulgee and Oconee River drainages in Bleckley, Greene, Harris, and Houston Counties, Georgia. The subpopulation from Harris County was reported after the assessment process and has not been verified. It is not reflected in the status of the species. Habitat loss and degradation resulting from logging activities and feral Pigs are the primary threats to the species. Rooting by feral Pigs disturbs the plants and has negatively impacted at least one subpopulation. Efforts undertaken by the Georgia Department of Natural Resources have prevented total extirpation of the species at two additional sites. Control of feral Pig populations is vital to the continued survival of the species, and additional efforts are needed to prevent further loss of the remaining T. delicatum subpopulations. The species is at a high risk of extinction due to its limited range, ongoing habitat loss and degradation, and continuing population decline.

Pale Trillium (Trillium discolor) is endemic to the upper Savannah River drainage in Georgia, North Carolina, and South Carolina. Within its limited range, it is locally frequent in mixed deciduous forests on rich soils, upland slopes, and floodplains. Live plants are sold in ornamental plant markets, and wild collection may negatively impact the species’ population. Other threats include habitat loss due to residential development, herbivory pressure associated with an overabundance of White-tailed Deer, disturbance caused by feral Pigs, silviculture, and logging. Most known subpopulations occur in protected areas, but the overwhelming majority of available habitat occurs on private land. Due to the species’ restricted range and habitat decline inferred from known threats, it is at moderate risk of extinction.

Red List Assessor(s): Trillium Working Group 2019 & Meredith, C.R.

NatureServe Global Rank Reviewer(s): Oliver, L.

Red List Assessor(s): Trillium Working Group 2019 & Meredith, C.R.

Refs: 1, 11–14, 29, 48, 49, 54, 55, 57, 59, 69–74, 76, 77, 81, 83–86, 102, 104, 110, 113, 123, 124, 130, 133, 134

NatureServe Global Rank Reviewer(s): Tomaino, A. Refs: 1, 11, 15, 48, 49, 55, 57, 58, 69, 71–74, 76, 83, 84, 86, 132

Trillium erectum

Trillium flexipes

Raf.

Pedicellate Least Concern Secure (G5) CA: NB, NS, ON, QC US: AL, CT, DC, DE, GA, ILU, IN, KY, MA, MD, ME, MI, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VA, VT, WV

Pedicellate Least Concern Secure (G5) CA: ON US: AL, AR, GA, IA, IL, IN, KY, MD, MI, MN, MO, MS, NC, NY, OH, PA, SD, TN, VAH, WV, WI

Red Trillium (Trillium erectum) is widely distributed in the Appalachian mountain range from northern Georgia north to New Brunswick, Nova Scotia, and southern portions of Quebec. The species is also present within the Great Lakes region and occurs in Ohio, throughout the Lower Peninsula of Michigan, portions of southern Ontario, and possibly northern Illinois. It is locally common in favorable, undisturbed habitats. Medicinal preparations including Red Trillium are commercially available and demand is thought to be rising. It is widely collected for the medicinal plant trade with most collection occurring in the southern Appalachian Mountains. The species is threatened by habitat degradation from introduced wild Pigs, introduced earthworm species in northern portions of the species’ range, herbivory pressure associated with an overabundance of White-tailed Deer, mining, and acid rain. Despite several threats that seriously impact localized subpopulations, the species is extremely widespread and considered to be at low risk of extinction.

Drooping Trillium (Trillium flexipes) occurs from northern Alabama north to northeastern South Dakota, and New York. Isolated occurrences can also be found in the Piedmont region east of the Appalachian Mountains, notably in Pennsylvania, Maryland, and North Carolina. The species’ population is inferred to be large but may be declining due to herbivory pressure from overabundant White-tailed Deer. Other threats to the species include habitat disturbance caused by feral Pigs, and competition with non-native plants including Winter Creeper and Garlic Mustard. This species prefers calcareous soils and occurs on wooded slopes and floodplains under deciduous tree canopies. Because of its large range and inferred large population, the species is not considered to be at substantial risk of extinction in the foreseeable future. However, given the declines noted in portions of its range, additional population monitoring should be conducted.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

NatureServe Global Rank Reviewer(s): Frances, A.

NatureServe Global Rank Reviewer(s): Treher, A.

Refs: 1, 11, 13, 14, 24, 32, 48, 49, 54, 57, 59, 64, 69, 71–74, 76, 77, 81, 83, 84, 86, 91, 92, 102, 108, 113, 131, 145–148

Refs: 1, 11–13, 24, 25, 48–50, 54, 59, 64, 69, 71–78, 81, 83, 84, 86, 92, 109, 117, 118, 120, 135–144

Trillium foetidissimum

Trillium georgianum

J.D.Freeman

S.B. Farmer

Sessile Least Concern US: LA, MS

Pedicellate Critically Endangered B1ab(iii,v)+2ab(iii,v) Critically Imperiled (G1) US: GA

Vulnerable (G3)

Mississippi River Trillium (Trillium foetidissimum) occurs in southeastern Louisiana, and southwestern Mississippi. The species is described as locally abundant in the Upper Coastal Plain within its range, but the population is thought to be declining. It occurs on slopes adjacent to riparian areas on loess soils in hardwood forests, and in association with azaleas (Rhododendron spp.). It is tolerant of a wide range of soil moistures and can be found in drier, upland areas in addition to riparian areas. The primary threats impacting Mississippi River Trillium are habitat loss and degradation due to logging, silviculture, and urban sprawl. Habitat degradation caused by feral Pigs and introduced competing plants, namely Chinese Privet, likely threaten some subpopulations. Given the species’ restricted range, and the presence of several threats, the species is vulnerable to population declines that may threaten its longterm survival. Additional monitoring is recommended to better determine the population trend of this species.

Georgia Dwarf Trillium (Trillium georgianum) is endemic to Whitfield County, Georgia where it is known from only a single location occurring within the drainage of Swamp Creek, a tributary of the Conasauga River. Previously considered to be a variety of T. pusillum, T. georgianum was published as a distinct species in 2017. Little is known about the species’ habitat and ecology, although it primarily reproduces vegetatively, an unusual trait within the genus. Its habitat is characterized by seasonally wet, shallow depressions. Within these depressions it is found on small, mounded islets on expansive clay soils in association with Red Maple (Acer rubrum), Green Ash (Fraxinus pennsylvanica), Black Gum (Nyssa sylvatica), and Oaks (Quercus spp.). The species is threatened by construction associated with industrial development, occurs in a single location, and has an extremely restricted range. It is at a very substantial risk of extinction, and protective measures are urgently needed to ensure the species’ survival.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

NatureServe Global Rank Reviewer(s): Treher, A.

Refs: 1, 11–13, 15, 29, 32, 48, 49, 54, 55, 59, 69, 71–74, 76, 81, 83, 84, 86, 101, 110, 113, 124, 133, 149, 150

Refs: 1, 11, 25, 48, 57, 58, 69, 71–74, 76, 81, 83–86, 109, 151

Trillium gracile

Trillium grandiflorum

J.D.Freeman

(Michx.) Salisb.

Sessile Near Threatened B2b(iii) US: LA, TX

Pedicellate Least Concern Secure (G5) CA: NBU, NS, ON, QC US: AL, CTU, DC, GA, IL, IN, KY, MAI, MD, MEUH, MI, MN, NC, NHU, NJ, NY, OH, PA, SC, TN, VA, VT, WI, WV

Imperiled (G2G3)

Slender Trillium (Trillium gracile) occurs on the Gulf Coast Plain of Louisiana and Texas in the Sabine River drainage. The species has a small range and a relatively restricted habitat type, occurring in mature, relatively open, hardwood pine and mixed deciduous forests, often on banks and ridges in sandy soils. Slender Trillium is occasionally planted as an ornamental. The primary threats to the species are logging, silviculture, and land use changes associated with expansion of urban areas. Remaining forests within the species’ range are highly fragmented by rights of way, pastureland, and urban development; a pattern that has increased in recent years. The species is likely undergoing population declines associated with habitat loss and degradation.

White Trillium (Trillium grandiflorum) occurs from southern Canada to the southern Appalachian Mountains and is abundant in preferred habitats. The root of the plant is used for various medical applications, though intensity of collection is not well understood. Widespread population declines attributable to herbivory pressure associated with an overabundance of White-tailed Deer have been noted in northern portions of the species’ distribution and are inferred to be present in southern portions. Inferring the population trend to the entire species’ range from observed decline in subpopulations, suggests rapid and substantial decline. It is important to note, however, that the impact of herbivory pressure is not necessarily permanent, nor are the observed rates of decline stable or consistent across the species’ range. The transition of flowering, reproductive individuals to nonreproductive stage classes fluctuates over time depending on resources and threats, and this modulation could mitigate overall predation pressure. For these reasons, along with the expansive range of the species and its large population, the species is not considered to be at risk of extinction.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Treher, A. & Frances, A. Refs: 1, 11, 13, 15, 29, 32, 48, 49, 54, 55, 57, 59, 64, 69, 71–74, 76, 77, 81, 83, 84, 86, 101, 110, 113, 152, 153

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Oliver, L. Refs: 1, 11–13, 25, 26, 28, 30, 32, 48–50, 54, 57, 64, 69, 71–74, 76, 78, 81, 83, 84, 86, 91, 92, 107, 113, 120, 135, 148, 154, 155

Trillium kurabayashii

Trillium lancifolium

J.D.Freeman

Raf.

Sessile Vulnerable D1 US: CA, OR

Sessile Endangered B2ab(iii,v)* US: AL, FL, GA, MS, SC, TN

Vulnerable (G3)

Giant Purple Trillium (Trillium kurabayashii) occurs in the Klamath and Coast Ranges of northern California and southwestern Oregon, in two distinct subpopulations. It occurs in a variety of forest types including moist coniferhardwoods and deciduous flat woods along streams. The species is occasionally planted as an ornamental, with some nurseries indicating propagation from wild collected seeds. The impact of collection on wild subpopulations is unknown. Little is known about threats to the species, but logging, suppression of natural fire regimes, predation by Elk, and competition with invasive plants including Himalayan Blackberry are likely to impact the species. The population size is estimated to be between 1,000 and 3,000 individuals, and may be closer to the lower limit if based on the number of reproductive individuals. More research is needed on distribution, population size and trend, habitats and ecology, and threats. Specifically, the population in the Sierra Nevada Mountains requires further study to determine its taxonomic status. It is considered to be at moderate risk of extinction.

Vulnerable (G3)

Narrow-leaved Trillium (Trillium lancifolium) occurs in disjunct subpopulations that extend from northwest Florida through eastern Tennessee. The species occurs over a wide range but is severely fragmented and occupies a very small area. Narrow-leaved Trillium is threatened by herbivory from an overabundance of White-tailed Deer, habitat degradation caused by feral Pigs, and logging operations throughout its range. Given its small range and abundance, severely fragmented population, and inferred declines in both habitat quality and number of mature individuals, the species is at moderate to high risk of extinction. The isolated nature of the species is well suited for habitat protection measures, which may be necessary to protect existing subpopulations from further habitat degradation. *The Red List includes T. tennesseense as a synonym of T. lancifolium while NatureServe considers the two taxa as distinct species. Both taxa are presented here separately in the narrowest sense.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

Red List Assessor(s): Wayman, K.A., Meredith, C.R. & Trillium Working Group 2019

NatureServe Global Rank Reviewer(s): Treher, A. & Frances, A.

NatureServe Global Rank Reviewer(s): Oliver, L. & Wayman, K.

Refs: 1, 11–15, 25, 32, 48, 49, 54, 55, 57, 59, 69, 71–74, 76, 77, 81–86, 101, 104, 108, 113, 130, 131, 134, 160–162

Refs: 1, 11, 12, 15, 42, 48, 49, 54–57, 59, 61, 66, 69, 71–74, 76, 83, 84, 86, 91–93, 101, 110, 156–159

Trillium ludovicianum

Trillium luteum

Harb.

(Muhl.) Harb.

Sessile Least Concern US: LA, MS, TX

Sessile Least Concern Apparently Secure (G4) CA: ONI US: ALU, DCI, GA, KY, MDI, MII, NC, SCU, TN, VAI

Apparently Secure (G4)

Louisiana Trillium (Trillium ludovicianum) occurs in northern Louisiana and limited adjacent portions of Mississippi and Texas. It occurs in floodplains, streambanks, and ravine forests in low-lying moist areas in mixed pinebeech forests. The species is locally abundant, but is threatened by habitat loss associated with development, herbivory from overabundant White-tailed Deer, and habitat degradation from feral Pigs. The population trend for the species is unknown. Due to the relatively large distribution of the species, and presumed large population, the species is at low risk of extinction.

The native range of Yellow Trillium (Trillium luteum) is in the southern Appalachian Mountains, from northern Georgia through eastern Tennessee and western North Carolina as well as portions of southern Kentucky. It has escaped from cultivation and become established in Michigan and Ontario, and is considered not native to Virginia, Maryland, and several other states. The species is described as abundant in the Ridge and Valley Province and locally abundant in the vicinity of Great Smoky Mountains National Park, particularly near Gatlinburg, Tennessee. It can tolerate disturbance and its population is thought to be stable. It occurs in deciduous forests, in thin open woods, clearings, old fields, riparian areas, and mature forests, typically on rocky calcareous or granitic substrates. The species is threatened by logging and land conversion, habitat disturbance caused by feral Pigs, and excessive herbivory from overabundant White-tailed Deer. Among the sessile Trillium species, Yellow Trillium is the most widely cultivated species. Most horticultural specimens are collected from the wild. Given its moderately large range and inferred large population, the species is thought to have a low extinction risk.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Treher, A. & Frances, A. Refs: 1, 11–15, 29, 32, 48, 49, 55, 57, 59, 69, 71–74, 76, 77, 81, 83, 84, 86, 101, 110, 113, 124, 150, 163

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Frances, A. Refs: 1, 11, 12, 14, 32, 48, 49, 54, 55, 57, 59, 64, 69, 71–74, 76, 83, 84, 86, 101, 104, 108, 110, 113, 164–166

Trillium maculatum

Trillium nivale

Raf.

Riddell

Sessile Data Deficient US: AL, FL, GA, SC

Pedicellate Least Concern Apparently Secure (G4) US: IL, IN, IA, KY, MD, MI, MN, MO, NE, OH, PA, SD, VA, WI, WV

Apparently Secure (G4)

Snow Trillium (Trillium nivale) has a broad distribution ranging from Maryland to South Dakota and from Missouri to Minnesota, but is rare or infrequent throughout much of its range. The species is among the earliest to bloom in spring. It occurs in calcareous, rocky soils often associated with limestone crevices, gravel deposits, sandy river terraces, and cliff bases. The species grows best in areas with little leaf litter, and very little competition with other herbaceous species. It may be threatened by habitat loss, and herbivory associated with overabundance of White-tailed Deer. Though its population trend is uncertain, very large subpopulations persist in portions of the species’ range and the species is thought to be at relatively low risk of extinction.

Spotted Trillium (Trillium maculatum) occurs in the Upper Coastal Plain and Piedmont regions from Alabama, and northern Florida to Georgia, and South Carolina. It occurs on granitic and calcareous substrates including coquina limestone, and shell middens in rich mesic woodlands. The species is very long lived and susceptible to population declines over time; however, the species’ population is still inferred to be large. Spotted Trillium is threatened by herbivory from overabundant White-tailed Deer and competition with competing invasive species including Chinese Privet. Browsing by expanding White-tailed Deer populations is suspected to be causing long-term declines in population throughout the species’ range, but additional research is needed to quantify these declines. Because the declines in the species are poorly understood, and that this species may qualify for a more threatened status based on these population declines, it is currently assessed as Data Deficient by the Red List. Due to its relatively large range and moderate threat level, it is considered Apparently Secure by NatureServe.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Oliver, L. & Frances, A. Refs: 1, 11–13, 25, 26, 32, 48, 49, 54, 55, 57, 59, 69, 71–74, 76, 81, 83, 84, 86, 107, 110, 113, 142, 168–180

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Treher, A. Refs: 1, 11, 13–15, 32, 48, 49, 54, 55, 57, 59, 69, 71–74, 76, 81, 83, 84, 86, 101, 104, 108, 110, 113, 163, 167

Trillium oostingii

Trillium ovatum

Gaddy

Pursh

Sessile Endangered B1ab(v)+2ab(v) Critically Imperiled (G1) US: SC

Pedicellate Least Concern CA: AB, BC US: CO, CA, ID, MT, OR, WA, WY

Secure (G5)*

Pacific Trillium (Trillium ovatum) is a species complex, with recent evidence indicating it includes five distinct species. Given the current uncertain status of taxa formerly recognized as infraspecies of T. ovatum, these taxa are presented here as a species complex. In addition to T. ovatum, the complex includes T. crassifolium, T. hibbersonii, and T. scouleri, which NatureServe recognizes at the species level, and are treated as such in this booklet. The Red List treats these four taxa within T. ovatum but includes an analysis documenting the impact of future taxonomic changes which is presented here. In the narrowed sense, T. ovatum can be further subdivided into T. ovatum subsp. ovatum and T. ovatum subsp. oettingeri. Accounts for these concepts are also included below. Trillium ovatum sensu lato is not considered to be at risk of extinction. Wateree Trillium (Trillium oostingii) is known only from Kershaw and Richland Counties, South Carolina. Twenty occurrences are known southwest of Camden, South Carolina and along the Wateree River, at elevations ranging from 50 to 100 meters. It occurs in four subpopulations on nutrient rich floodplains, levees, and flats along the Wateree River and is locally abundant with thousands of stems described in some occurrences. The species is rarely available as an ornamental, and collection for the ornamental trade has occurred, but the impact of such collection is thought to be minor. Rooting from feral Pigs and erosion along levee banks have caused slight population declines. Other potential threats to the species include herbivory from overabundant White-tailed Deer, and competition with invasive Chinese Privet. Portions of the species’ habitat are protected, but additional population monitoring is needed to better conserve the species. Due to its very restricted range, presence in only four locations, and continuing population decline, the species is at high risk of extinction.

Red List Assessor(s): Meredith, C.R., Schilling, E.E. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Oliver, L. Refs: 1, 11, 13, 42, 46, 48, 49, 54, 55, 57, 59–61, 66, 67, 69, 71-74, 76, 83, 84, 86, 91–93, 120, 156, 157, 183–192

Red List Assessor(s): Meredith, C.R., Trillium Working Group 2019, Farmer, S.B. & Gaddy, L.L. NatureServe Global Rank Reviewer(s): Treher, A. & Frances, A. Refs: 1, 11, 32, 48, 49, 54, 55, 57, 69, 71–74, 76, 81, 83, 84, 86, 113, 181, 182

NatureServe

Red List Proposed

subsp. ovatum

subsp. oettingeri

Red List as Published

Trillium ovatum

Trillium crassifolium

Trillium hibbersonii

Trillium scouleri

Table 4: Comparison of taxonomic distinctions recognized by NatureServe and the Red List.

Trillium ovatum

Trillium crassifolium

Trillium hibbersonii

Piper

(T.M.C. Taylor & Szczaw.) D. O’Neill & S.B. Farmer

Pedicellate Data Deficient* US: WA

Pedicellate Endangered B2ab(iii)* CA: BC

Critically Imperiled (G1G2)

Trillium crassifolium was described in the late 1800s, but was treated as part of T. ovatum. Recent molecular work has revealed that the older interpretation of crassifolium as a distinct species is accurate. It is endemic to the Wenatchee Mountains of central Washington. Very little is known about this taxon, including the extent of its range, threats, and population size. It is considered to be at high risk of extinction. *The Red List includes Trillium as a synonym of Trillium ovatum Pursh

Vulnerable (G3)

Hibberson’s Trillium (Trillium hibbersonii) was treated as variety of T. ovatum until recently but was published as a species in 2020. It has a very limited range, with known occurrences in only four remote and inaccessible areas on the Pacific Coast of Vancouver Island, British Columbia. It is threatened by logging in adjacent areas. Climate change that would affect the hydrology of the seep habitats where it occurs is also considered a threat. Given its very limited distribution, small number of known occurrences, and the threats to the taxon, notably from logging, it is at a moderate risk of extinction.

crassifolium

*The Red List includes Trillium as a synonym of Trillium ovatum Pursh

Red List Assessor(s): Meredith, C.R., Schilling, E. & Trillium Working Group 2019

hibbersonii

NatureServe Global Rank Reviewer(s): Oliver, L. & Wayman, K.A.

Red List Assessor(s): Meredith, C.R., Schilling, E.E. & Trillium Working Group 2019

Refs: 1, 11, 13, 42, 46, 48, 49, 54, 55, 57, 59–61, 66, 67, 69, 71-74, 76, 83, 84, 86, 91–93, 120, 156, 157, 185–192

NatureServe Global Rank Reviewer(s): Penny, J. & Oliver, L. Refs: 1, 11, 13, 42, 46, 48, 49, 54, 55, 57, 59–61, 66, 67, 69, 71–74, 76, 83, 84, 86, 87, 91–93, 120, 156, 157, 185–192

Trillium ovatum var. oettingeri

Trillium ovatum var. ovatum

Munz & Thorne

Pursh.

Pedicellate Data Deficient* US: CA

Pedicellate Least Concern* CA: BC US: CA, OR, WA

Apparently Secure (T4)

Secure (T5)

Red List Assessor(s): Meredith, C.R., Schilling, E.E. & Trillium Working Group 2019

Trillium ovatum var. ovatum occurs from British Columbia through Washington, Oregon, and California within mountainous areas along the coast. The species often occurs in association with Douglas-fir (Pseudotsuga menziesii) but may also be found in forests dominated by Western Red Cedar (Thuja plicata), Western Hemlock (Tsuga heterophylla), Bigleaf Maple (Acer macrophyllum), Red Alder (Alnus rubra), and Sitka Spruce (Picea sitchensis). The root of the plant has been used to treat sore eyes by the Lummi, Paiute, Skagit, and Thompson. The taxon is intolerant of logging and may require centuries to recover from clearcutting. Observed rates of decline in some subpopulations exceed 95% to clearcutting. Despite the threat posed by logging, the species has a robust population in California and is unlikely to be at risk of extinction.

NatureServe Global Rank Reviewer(s): Oliver, L., Wayman, K., & Treher, A.

*The Red List includes Trillium ovatum stricto as a synonym of Trillium ovatum Pursh

Trillium ovatum var. oettingeri is endemic to northern California and occurs entirely in protected areas. It is found within the Klamath and Shasta-Trinity National Forests. Wildfires have impacted some areas and perhaps caused substantial population declines. With that said, the subpopulations are protected from logging and other disturbances. The taxon is considered to be at relatively low risk of extinction. *The Red List includes Trillium ovatum var. oettingeri as a synonym of Trillium ovatum Pursh

Refs: 1, 11, 13, 42, 46, 48, 49, 54, 55, 57, 59–61, 66, 67, 69, 71–74, 76, 83, 84, 86, 91–93, 93, 120, 156, 157, 185–193

sensu

Red List Assessor(s): Meredith, C.R., Schilling, E.E. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Oliver, L. Refs: 11, 13, 42, 46, 54, 55, 59–61, 66, 67, 91–93, 120, 156, 157, 185–192

Trillium scouleri

Trillium persistens

Rydb. ex Gleason

Duncan

Pedicellate Least Concern* Apparently Secure (G4G5) CA: AB, BC US: CO, ID, MT, OR, WA, WY

Pedicellate Vulnerable D2 US: GA, SC

The taxonomic status of Trillium scouleri is unclear, however, it was historically recognized at the species level and recent genetic evidence suggests this interpretation is likely to be revisited. It occurs in the Northern Rocky Mountains from the Thompson Plateau of British Columbia, south through easternmost Washington and Oregon, extending nearly to the Snake River Plain in Idaho, and including the mountains of westernmost Montana. Disjunct subpopulations also occur in the Absaroka, Beartooth, and Gallatin Ranges of Montana and Wyoming, and in the Park Range of Colorado and Wyoming. Population trend, habitats, and the threats to the species are poorly documented, but the species occurs across a broad range in many remote, protected areas. As such, it is considered to have a low risk of extinction.

Persistent Trillium (Trillium persistens) is found only in and around Tallulah Gorge in Habersham, Rabun, and Stephens Counties, Georgia and Oconee County, South Carolina. The species inhabits steep slopes under mixeddeciduous forest canopies. Although additional population surveys are needed to determine current population size and trends, the species is thought to have a relatively stable population of approximately 20,000 stems. The species was previously threatened by habitat degradation caused by logging and recreational usage, however, most of these threats have been mitigated and the species is considered well protected. Given the species’ extremely restricted range, it is still susceptible to stochastic events or substantial alterations of its limited habitat. Ongoing habitat quality decline caused by the Hemlock Woolly Adelgid may impact the entire population. Because it has a very restricted distribution and is subject to a potential threat that could cause rapid population declines, it is considered to be at a moderate to high risk of extinction.

*The Red List includes Trillium as a synonym of Trillium ovatum Pursh

scouleri

Critically Imperiled (G1)

Red List Assessor(s): Meredith, C.R., Schilling, E.E. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Oliver, L.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

Refs: 1, 11, 13, 42, 46, 48, 49, 54, 55, 57, 59–61, 66, 67, 69, 71–74, 76, 83, 84, 86, 91–93, 120, 156, 157, 184–192

NatureServe Global Rank Reviewer(s): Treher, A. & Frances, A. Refs: 1, 11, 12, 25, 48, 49, 55, 57, 69, 71–74, 76, 83, 84, 86, 113, 131, 138, 194–199

Trillium petiolatum

Trillium pusillum

Pursh

Sessile Least Concern US: ID, OR, WA

Pedicellate Least Concern Apparently Secure (G4) US: AL, AR, GA, KY, MD, MO, MS, NC, OK, SC, TN, VA, WV

Apparently Secure (G4)

Dwarf Trillium (Trillium pusillum) occurs in the southeastern United States and has a widely disjunct distribution comprised of highly variable regional subpopulations. Research is underway to investigate the distribution patterns and taxonomy of the T. pusillum species complex and the conservation status of infraspecies within the complex is highly dependent on the outcome of this research. The assessments presented here follow the numbering system employed by Weakley. Future research may validate recognition of these varieties at the species rank. Two taxa formerly considered part of T. pusillum (T. texanum and T. georgianum) are treated in this text at the species level and are listed elsewhere in this volume. The species complex can be divided into three clusters. The Virginianum Cluster consists of published varieties monticulum and virginianum. Two additional taxa, variety 4 and variety 5, will likely be split from variety virginianum when formally published. The Ozarkanum Cluster is composed of the published variety ozarkanum, from which the putative variety 1 will likely be split. The Pusillum Cluster is composed of variety pusillum and the putative variety 3.

Idaho Trillium (Trillium petiolatum) occurs in northern Idaho and eastern Oregon and Washington. Found in association with a variety of forest types, it is tolerant of more xeric conditions than other western Trillium species. Population size and trends are not well understood and research is needed to better understand the threats and related population dynamics. Despite these uncertainties, the species has a relatively large range and is noted to be locally abundant in areas with favorable habitat. Given its wide range and absence of specific threats, the species is listed at a low risk of extinction.

Considered as a species complex (and excepting T. texanum and T. georgianum), Dwarf Trillium is at low risk of extinction. The combined ranges of its constituent varieties extend from West Virginia south to South Carolina and west to Oklahoma. Its habitats and major threats are quite varied (as described below), but aggregate populations are robust.

Red List Assessor(s): Meredith, C.R., Wayman, K.A. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Oliver, L. & Wayman, K.

Red List Assessor(s): Meredith, C.R., Schilling, E.E. & Trillium Working Group 2019

Refs: 1, 11, 13, 48, 49, 54, 55, 57, 61, 68, 69, 71–74, 76, 83, 84, 86, 91–93, 120, 200

NatureServe Global Rank Reviewer(s): Oliver, L. Refs: 1, 11–15, 24, 25, 30, 33, 48, 49, 55, 57, 69, 71–74, 76, 81, 83–86, 91, 92, 102, 122, 131, 138, 141, 164, 173, 201–217

NatureServe

Trillium pusillum var. ozarkanum

Farmer/Red List Proposed/Weakley

Red List as Published

Trillium ‘ozarkanum’ (= T. pusillum var. ozarkanum) Trillium ‘alabamicum’ (= T. pusillum var. 1) Trillium virginianum

Trillium pusillum var. virginianum

Trillium ‘carolinianum’ (= T. pusillum var. 4) Trillium ‘palustris’ (= T. pusillum var. 5)

Trillium pusillum var. monticulum

Trillium pusillum var. pusillum

Trillium pusillum

Trillium ‘monticulum’ (= T. pusillum var. monticulum’) Trillium pusillum ( = T. pusillum var. pusillum) Trillium ‘telmacola’ (= T. pusillum var. 3)

Trillium georgianum

Trillium texanum

Table 5: Comparison of T. pusillum taxonomic frameworks recognized by NatureServe and the Red List.

Trillium pusillum var. monticulum

Trillium pusillum var. virginianum

Bodkin & Reveal

Fernald

Pedicellate Endangered B1ab(iii)+2ab(iii)* Imperiled (G4T2) US: VA, WV

Pedicellate Vulnerable B1ab(iii)* US: VA

Trillium pusillum var. monticulum is part of the Virginianum cluster. It occurs in northwest Virginia in Augusta and Rockingham Counties, and eastern West Virginia, in Pendleton County. The taxon is restricted to ridgelines associated with the crest of Shenandoah Mountains. It is likely that this variety will be elevated to the species level. The taxon is known from only two locations, and recent population data for the species is not available, however, at the time of its description (1982), each subpopulation consisted of 300 stems. It occurs in dry or dry-mesic woodlands, meadow margins, and relatively open areas. Due to its limited distribution and several ongoing threats in the region, the species is considered to be at extremely high risk of extinction.

Trillium pusillum var. virginianum occurs in swamps only on the upper Coastal Plain of southeastern Virginia and is found from Henrico east to Mathews Counties, and south to Brunswick and Greensville Counties. Fewer than 10,000 individuals are thought to exist in no more than 55 occurrences. Habitat quality for the species continues to decline as a result of competition with invasive species, urban expansion, habitat degradation caused by feral Pigs, and herbivory by overabundant White-tailed Deer. Additional population surveys are needed as several subpopulations have not been observed in more than 30 years. Due to its narrow range and the numerous threats to the taxon, it is considered to be at high risk of extinction.

Imperiled (G4T2)†

*The Red List includes Trillium pusillum var. virginianum under its treatment of Trillium pusillum

*The Red List includes Trillium pusillum var. monticulum under its treatment of Trillium pusillum

† This Global Rank is provisional and not available on NatureServe Explorer because the taxon is not formally published.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Treher, A.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

Refs: 1, 11–15, 24, 25, 30, 33, 48, 49, 55, 57, 69, 71–74, 76, 81, 83–86, 91, 92, 102, 138, 141, 164, 201–212

NatureServe Global Rank Reviewer(s): Treher, A. Refs: 1, 11–15, 24, 25, 30, 33, 48, 49, 55, 57, 69, 71–74, 76, 81, 83–86, 91, 92, 102, 138, 141, 164, 201–212

Trillium pusillum var. 4

Trillium pusillum var. 5

Pedicellate Vulnerable B1ab(i,iii,iv,v)* US: NC, VAH

Pedicellate Vulnerable B1ab(iii)* Vulnerable (G4T3) † US: MD, NC, VA

Vulnerable (G4T3)†

Carolina Trillium (Trillium pusillum var. 4) occurs primarily along the Fall Line ranging from Johnston to Halifax Counties, North Carolina. A historic subpopulation in Grayson County, Virginia could not be relocated during surveys conducted in 2001. The taxon’s population is not well understood, but repeated surveys suggest it is in decline. It occurs in a region undergoing rapid population growth, and may be threatened by habitat loss and competition with introduced plant species. However, the taxon occurs in two protected areas and some subpopulations may be adequately protected. Due to its limited range, the presence of several threats, and the relatively recent loss of a historic subpopulation, the taxon is considered at moderate risk of extinction.

Vulnerable(G4T3)†

Dismal Swamp Least Trillium (Trillium pusillum var. 5) occurs in the southernmost portions of the Delmarva Peninsula, and five counties in North Carolina and Virginia in the vicinity of the Great Dismal Swamp. The population of the taxon is poorly understood, but a total of nine occurrences have been documented. It is confined to low-lying wetland habitats making it susceptible to disturbance from feral Pigs. It may also be negatively impacted by forest clearance and wetland drainage. Urban development within counties included in the species’ range is among the most rapid in the state of North Carolina, and further development in the region is likely. Due to the species’ limited distribution, and the threat of habitat loss and degradation, the species is considered to be at moderate risk of extinction.

*The Red List includes Trillium pusillum var. 4 under its treatment of Trillium pusillum.

*The Red List includes Trillium pusillum var. 5 under its treatment of Trillium pusillum

† This Global Rank is provisional and not available on NatureServe Explorer because the taxon is not formally published.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

Refs: 1, 11–15, 24, 25, 30, 33, 48, 49, 55, 57, 69, 71–74, 76, 81, 83–86, 91, 92, 102, 122, 131, 138, 141, 164, 173, 201–217

Trillium pusillum var. ozarkanum

Trillium pusillum var. 1

(E.J. Palmer & Steyerm.) Steyerm. Pedicellate Least Concern* US: AL, TN

Pedicellate Least Concern* Vulnerable (G4T3) US: AR, KY, OK, MO, MS, NC, TN

Vulnerable (G4T3)†

Alabama Trillium (Trillium pusillum var. 1) occurs from Alabama’s interior southern highland rim from Marshall and Morgan Counties, north to Tennessee in Putnam County. The taxon is relatively abundant with population estimates suggesting many thousands of adults are present within its range. The taxon is most commonly found in wetland habitats, but has shown considerable flexibility in habitat preference. Population declines may be ongoing as a result of habitat disturbance from feral Pigs and competition with introduced plant species, but these are not thought to present a substantial risk to the taxon as a whole. Its extinction risk is considered low.

Within the Trillium pusillum species complex, Ozark Trillium (Trillium pusillum var. ozarkanum) is the most broadly distributed and abundant member. Though it has been historically considered a variety, it may be elevated to the species level. It occurs in the Ozark Mountains of southwest Missouri, northwest Arkansas, and eastern Oklahoma. Disjunct subpopulations of Ozark Trillium also occur in south central Kentucky, north central Tennessee (Sumner County), and southwest North Carolina (Clay and Haywood Counties), and in Jones County, Mississippi. The putative variety Trillium pusillum var. 1 would be split from Trillium pusillum var. ozarkanum from occurrences in northern Alabama and central Tennessee. These materials have been excluded here in discussions of var. ozarkanum. Its habitat requirements are broad, and the taxon occurs in relatively dry areas to wetlands. The primary threats to the taxon are logging and overabundance of White-tailed Deer. Due to its wide range and large population, the taxon is considered to be at low to moderate risk of extinction.

*The Red List includes Trillium pusillum var. 1 under its treatment of Trillium pusillum † This Global Rank is provisional and not available on NatureServe Explorer because the taxon is not formally published.

*The Red List includes Trillium pusillum var. ozarkanum under its treatment of Trillium pusillum

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

Refs: 1, 11–15, 24, 25, 30, 33, 48, 49, 55, 57, 69, 71–74, 76, 81, 83–86, 91, 92, 102, 122, 131, 138, 141, 164, 173, 201–217

NatureServe Global Rank Reviewer(s): Treher, A. Refs: 1, 11–15, 24, 25, 30, 33, 48, 49, 55, 57, 69, 71–74, 76, 81, 83–86, 91, 92, 102, 138, 141, 164, 201–212

Trillium pusillum var. pusillum

Trillium pusillum var. 3

Pursh Pedicellate Least Concern* US: NC, SC

Pedicellate Critically Endangered D* Critically Imperiled (G4T1)† US: SC

Vulnerable (G4T3)

Dwarf Trillium (Trillium pusillum var. pusillum sensu stricto) occurs along the Coastal Plain of North Carolina in Brunswick and Pender Counties, and in several counties in South Carolina. Subpopulations in Williamsburg County, South Carolina are extirpated. In the narrowest interpretation, this taxon is thought to have a total population of fewer than 10,000 plants. It occurs in wetland habitats and is threatened primarily by habitat degradation caused by feral Pigs, and reduction of wetland areas caused by surrounding expanding urban areas. The taxon is considered to be at low to moderate risk of extinction. However, given the threats present within its range, and the increasing threat posed by feral Pigs, additional population monitoring may be warranted.

Aiken Least Trillium (Trillium pusillum var. 3) occurs in a very narrow distribution on the sand hills of the Savannah River Site on the border of Aiken and Barnwell Counties, South Carolina. The taxon’s population is extremely small with an estimated adult population composed of potentially fewer than 50 individuals. It occurs in wetland habitats and has been observed to prostrate itself upon pollination, a trait not noted for any other Trillium taxon. The Savannah River Site is noted to host large numbers of feral Pigs and overabundant White-tailed Deer. Habitat disturbance from the former is considered to be the most significant threat to the taxon. Population monitoring of this rare taxon is needed to determine its population trend, but its tendency to prostrate after very brief bloom periods complicates these efforts. Due to its very limited population, the taxon is considered to be at extremely high risk of extinction.

*The Red List includes Trillium pusillum sensu stricto under its treatment of Trillium pusillum

*The Red List includes Trillium pusillum var. 3 under its treatment of Trillium pusillum Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

† This Global Rank is provisional and not available on NatureServe Explorer because the taxon is not formally published.

NatureServe Global Rank Reviewer(s): Treher, A. Refs: 1, 11–15, 24, 25, 30, 33, 48, 49, 55, 57, 69, 71–74, 76, 81, 83–86, 91, 92, 102, 138, 141, 164, 201–212, 218, 219

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 Refs: 1, 11–15, 24, 25, 30, 33, 48, 49, 55, 57, 69, 71–74, 76, 81, 83–86, 91, 92, 102, 122, 131, 138, 141, 164, 173, 201–217

Trillium recurvatum

Trillium reliquum

Beck

J.D. Freeman

Sessile Least Concern Secure (G5) US: AL, AR, CTI, IL, IN, IA, KY, LA, MI, MO, MS, NC, NE, OH, OK, PAI, TN, TX, WI

Sessile Near Threatened US: AL, GA, SC

Prairie Trillium (Trillium recurvatum) occurs in the Mississippi River Basin from Alabama and Texas north to Iowa, Wisconsin, and Michigan. The species is relatively abundant within its range and occurs in a variety of forest communities and substrates. Threats to the species include herbivory pressure caused by the overabundance of White-tailed Deer and habitat disturbance associated with logging practices. The species is known to occur in several protected areas within its range. Because the species is abundant, relatively tolerant of habitat disturbance, and lacking evident population declines, it is at a low risk of extinction.

Relict Trillium (Trillium reliquum) has a disjunct distribution, with eastern subpopulations in Aiken and Edgefield Counties, South Carolina and adjacent portions of Georgia in Columbia and Burke County. Western subpopulations occur just east of Macon, Georgia to Bullock County, Alabama and from Henry County, Georgia in the north, to Miller County, Georgia in the south. The species occurs in mixed deciduous forests on slopes, bluffs, and the floodplains of riparian areas. Threats to the species include herbivory by overabundant White-tailed Deer, disturbance by feral Pigs, improper timing of prescribed fires, and invasive species including Japanese Stiltgrass, Chinese Privet, and Trifoliate Orange. The species is known to be in cultivation, but trade is thought to be minimal. Its population is thought to be in decline. The species was listed as Endangered in 1988 under the U.S. Endangered Species Act, but this protection does not extend to private land. Due to its relatively small range and large number of threats, this species is at moderate risk of extinction.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Treher, A. & Frances, A.

Vulnerable (G3)

Refs: 1, 11–13, 26, 32, 42, 48, 49, 54, 55, 57, 59, 64, 69, 71–74, 76, 81, 83–86, 104, 109, 113, 124, 131, 220–225 Red List Assessor(s): Meredith, C.R., Schilling, E.E. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Treher, A. Refs: 1, 11, 12, 25, 32, 48, 49, 55, 57, 59, 69, 71–74, 76, 77, 83–86, 91, 101, 109, 131, 168, 196, 197, 223, 225–231

Trillium rugelii

Trillium sessile

Rendle

Pedicellate Least Concern US: AL, GA, SC, NC, TN

Sessile Least Concern Apparently Secure (G4) US: AL, AR, DC, IL, IN, KS, KY, MD, MI, MO, NY, NC, OH, OK, PA, TN, VA, WV

Apparently Secure (G4)

Southern Nodding Trillium (Trillium rugelii) occurs in the southern Appalachian range and adjacent Piedmont areas from Alabama to North Carolina. The species is locally common in Georgia and is rare or uncommon elsewhere in its range. Its population is thought to be relatively stable. It is occasionally planted for ornamental purposes and may be included in herbal remedies marketed as bethroot. The species is threatened by habitat loss resulting from logging and silviculture operations, excessive herbivory caused by overabundance of White-tailed Deer, habitat quality declines associated with feral Pigs, and habitat loss due to residential and commercial development. Threats to the species are numerous and additional monitoring of population trends is warranted, but the species is considered to be at a low risk of extinction.

Sessile Trillium (Trillium sessile) occurs from western New York in Chautauqua County south to the coastal plain of North Carolina, west to extreme eastern portions of Oklahoma and Kansas, and north to southern Michigan. It occurs in rich woodlands under a variety of moisture regimes ranging from riverbanks and floodplains to dry upland woods. The species is abundant in portions of its range. Threats to the species include herbivory pressure caused by overabundance of White-tailed Deer, habitat degradation from feral Pigs, invasive plant species, and impacts from logging. Additional monitoring is needed to determine the population trajectory of the species, although it is currently thought to be stable. Due to a large population across vast areas of favorable habitat, this species is considered to be at low risk of extinction.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

NatureServe Global Rank Reviewer(s): Treher, A. & Frances, A.

NatureServe Global Rank Reviewer(s): Treher, A. Refs: 1, 11, 13, 14, 25, 29, 32, 42, 48, 49, 54, 55, 57, 59, 64, 69, 71–77, 81, 83–86, 101, 108, 109, 113, 120, 123, 160, 234

Refs: 1, 11–14, 25, 32, 48, 49, 55, 57, 59, 64, 69, 71–74, 76, 77, 81, 83–86, 104, 108–110, 117, 124, 228, 232, 233

Trillium simile

Trillium stamineum

Gleason

Harb.

Pedicellate Vulnerable B1ab(iii,v)+2ab(iii,v) US: GA, NC, SC, TN

Sessile Least Concern US: AL, KY, MS, TN

Vulnerable (G3)

Jeweled Wakerobin (Trillium simile) occurs in a restricted range within the southern Appalachian Mountains. It is found in rich cove forests and forest edges along the border of Tennessee and North Carolina, and south to northwestern South Carolina and northern Georgia. The species is known from 50 extant occurrences and has a relatively large population. The primary threats to the species include habitat degradation caused by feral Pigs, herbivory associated with overabundant White-tailed Deer, and habitat loss due to residential development. The species is considered to be at moderate risk of extinction due to declining habitat quality, and its restricted range.

Apparently Secure (G4)

Twisted Trillium (Trillium stamineum) is a long-lived spring wildflower that occurs in the southern United States. The species can be found from central Tennessee southward through Alabama and the eastern portions of Mississippi. It prefers open deciduous or mixed-deciduous forests on a variety of substrates. The peculiar shape of the species’ flowers makes it appealing to horticulturalists, though the current market is relatively small. The species is locally abundant in much of its range and is common in northern Alabama. Threats to the species are poorly understood, and additional research and population monitoring are needed. Due to its large population within a relatively expansive range, the species is at low risk of extinction.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

NatureServe Global Rank Reviewer(s): Treher, A. NatureServe Global Rank Reviewer(s): Treher, A. Refs: 1, 11–13, 32, 48, 49, 55, 57, 69, 71–74, 76, 77, 81, 83, 84, 86, 131, 142, 164, 179, 229, 235

Refs: 1, 11, 13, 25, 32, 48, 49, 54, 55, 57, 69, 71–74, 76, 81, 83–86, 101, 109

Trillium sulcatum

Trillium tennesseense

T.S.Patrick

E.E.Schill. & Floden

Pedicellate Least Concern Apparently Secure (G4) US: AL, GA, KY, NC, TN, VA, WV

Sessile Critically Endangered B1ab(iii,iv,v)+2ab(iii,iv,v)* Critically Imperiled (G1) US: TN

Barksdale Trillium (Trillium sulcatum) occurs predominantly on the Cumberland Plateau and in the central Blue Ridge Mountains and adjacent areas ranging from Alabama north to Kentucky. The species is locally common, though additional population data are needed to determine the population trend. It occurs in rich mesic forest habitats on a variety of substrates. Like other Trillium species, Barksdale Trillium is threatened by herbivory pressure from an overabundance of White-tailed Deer, habitat disturbance caused by feral Pigs, logging, and habitat loss to silviculture. Conservation efforts should focus initially on research to determine basic lifehistory, population trends, and the impact of threats to the species. Because the species is relatively common across a large area, it is considered to be at low risk of extinction.

Tennessee Trillium (Trillium tennesseense) is a narrow endemic of the Bays Mountain formation in Hamblen and Hawkins Counties, Tennessee. The taxon occurs in four small subpopulations on floodplains, along drainages, and on midslopes of Sevier shale formations. All known subpopulations are located on private land. The taxon is threatened by collection for horticultural purposes, competing invasive species, land conversion, and a fungal infection of unknown origin. The species is considered to be at an extremely high risk of extinction. *The Red List considers T. tennesseense as a synonym of T. lancifolium. Considered separately, T. tennesseense would qualify for listing as Critically Endangered under criteria B1ab(iii,iv,v).

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

NatureServe Global Rank Reviewer(s): Treher, A. NatureServe Global Rank Reviewer(s): Treher, A. & Frances, A.

Refs: 1, 11–15, 32, 48, 49, 54, 55, 57, 59, 69, 71–74, 76, 77, 81, 83, 84, 86, 110, 124, 164, 236–239

Refs: 1, 11–15, 32, 48, 49, 54, 55, 57, 59, 69, 71–74, 76, 77, 81, 83–86, 101, 104, 106, 108, 110, 113, 160–163

Trillium texanum

Trillium underwoodii

Buckley

Small

Pedicellate Vulnerable B2ab(iii) US: AR, LA, TX

Sessile Least Concern US: AL, FL, GA

Imperiled (G2)

Texas Trillium (Trillium texanum) is found in wetland areas of eastern Texas, northwest Louisiana, and southern Arkansas. The species occurs in 24 subpopulations scattered across its range in creek bottom bogs in association with mixed deciduous forests. Several threats to the species are known, primarily related to logging and hydrological changes. Five sites are known to have some level of official protection and two more are managed by the State of Texas or included in conservation easements. Given the pervasive nature of the threats to the species’ survival, namely wetland drainage and rooting caused by feral Pigs and that the species can be considered to occur in fewer than 10 locations the extinction risk is moderate to high risk.

Apparently Secure (G4)

Underwood’s Trillium (Trillium underwoodii) occurs in southern Alabama, southwestern Georgia, and northern Florida. Little is known about the species’ population, but several subpopulations are noted to be large. The species may be threatened by a variety of factors including herbivory from over abundant White-tailed Deer, habitat degradation caused by feral Pigs, and habitat loss due to urbanization and logging. Several invasive plants may also negatively impact the species including Japanese Stiltgrass, Bush Honeysuckle, English Ivy, Chinese Privet, and Trifoliate Orange. The magnitude of these threats is poorly understood, and additional research is needed. The species occurs across a relatively broad area, and no specific threats are known to have caused population declines. As such, the species is considered to have a low risk of extinction.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Treher, A.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

Refs: 1, 11–13, 15, 48, 49, 49, 55, 57, 57, 58, 69, 71–74, 76, 83, 84, 86, 124, 138, 153, 240, 241

NatureServe Global Rank Reviewer(s): Treher, A. Refs: 1, 11, 13, 14, 25, 48, 49, 54, 55, 57, 69, 71–74, 76, 77, 83–86, 101, 230

Trillium vaseyi

Trillium viride

Harb.

Beck

Pedicellate Near Threatened B1ab(iii) US: ALU, GA, NC, SC, TN

Sessile Least Concern US: IL, KYU, MO, TNU

Vulnerable (G3)

Vulnerable (G3G4)

Vasey’s Trillium (Trillium vaseyi) is a narrowly distributed endemic of the southern Blue Ridge Mountains. Subpopulations to the south extending into west-central Georgia and portions of Alabama are of dubious taxonomic status and it is doubtful that the species occurs in this area. Although little is known about the population, it is threatened within its range by high herbivory pressure from overabundant White-tailed Deer, and habitat degradation caused by rooting feral Pigs. Collection pressure for horticultural markets may also impact some subpopulations. Though much of the species’ range occurs within protected areas, these protections do not adequately address the threat posed by logging and invasive Hemlock Woolly Adelgid. Many protected areas within the species’ range are periodically logged, potentially leading to habitat degradation. Because the species has a limited distribution and undergoing ongoing habitat quality declines, it is thought to be at a moderate risk of extinction.

Green Trillium (Trillium viride) occurs in northeastern Missouri and southwestern Illinois on rich clay soils in counties adjacent to the Missouri River. The species is found on bluffs and rocky hillsides in woodland areas characterized by limestone substrates and rich clay soils. Little is known about the population size of this species primarily because of confusion with related species, and resulting disagreement over the species’ range. Several threats that impact Trillium species in eastern North America are likely to affect this species. This includes overabundance of White-tailed Deer, habitat destruction and degradation caused by logging, habitat degradation associated with feral Pigs, and competition with invasive plants. The impact of these threats on Green Trillium subpopulations is poorly understood, and additional research is needed to determine the population trend of the species. Because the species has a large population and no severe threats, it is thought to have a low to moderate risk of extinction.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019

NatureServe Global Rank Reviewer(s): Treher, A. & Frances, A.

Refs: 1, 11, 13–15, 25, 48, 49, 54, 55, 57, 69, 71–74, 76, 78, 81, 83–86, 108–110, 138, 229, 232, 242, 243

Refs: 1, 11–13, 15, 24, 25, 28–30, 48, 49, 55, 57, 69, 71–74, 76, 78, 81, 83–86, 108, 109, 123, 138, 164, 229, 244, 245

Trillium viridescens Nutt. Sessile Least Concern Apparently Secure (G4) US: AR, KS, LA, MO, OK, TX

Ozark Green Trillium (Trillium viridescens) occurs from southern Missouri and southeast Kansas to extreme eastern portions of Texas. The species is locally common throughout its range on rich clay soils on rocky bluffs, talus slopes, and floodplains. The population trend of the species is not currently known. Threats that may impact the species include herbivory pressure from overabundant White-tailed Deer, logging, habitat degradation caused by feral Pigs, and invasive plants including Burning Bush and Bush Honeysuckle. Because the species is locally common across a broad distribution, it is at a low risk of extinction.

Red List Assessor(s): Meredith, C.R. & Trillium Working Group 2019 NatureServe Global Rank Reviewer(s): Frances, A. Refs: 1, 11, 12, 15, 24, 25, 28–30, 48, 49, 54, 55, 57, 69, 71–74, 76, 78, 81, 83, 84, 86, 101, 108, 123, 138, 164, 216, 229, 246, 247

Photos

Figure 10: Trillium albidum subsp. albidum (K. Wayman)

Figure 8: Pseudotrillium rivale (K. Wayman)

Figure 11: Trillium albidum subsp. parviflorum (K. Wayman)

Figure 9: Trillidium undulatum (E.E. Schilling) Figure 12: Trillium angustipetalum (K. Wayman)

Figure 13: Trillium catesbaei (L.L. Gaddy) Figure 16: Trillium cuneatum (E.E. Schilling)

Figure 14: Trillium cernuum (K. Filicky)

Figure 17: Trillium decipiens (E.E. Schilling)

Figure 15: Trillium chloropetalum (K. Wayman)

Figure 18: Trillium decumbens (E.E. Schilling)

Figure 19: Trillium delicatum (E.E. Schilling)

Figure 21: Trillium erectum (T. Littlefield)

Figure 20: Trillium discolor (E.E. Schilling)

Figure 22: Trillium flexipes (T. Littlefield)

Figure 23: Trillium foetidissimum (Mt. Cuba Center)

Figure 26: Trillium grandiflorum (T. Littlefield)

Figure 24: Trillium georgianum (E.E. Schilling)

Figure 27: Trillium kurabayashii (K. Wayman)

Figure 25: Trillium gracile (J. Singhurst)

Figure 30: Trillium luteum (E.E. Schilling)

Figure 28: Trillium lancifolium (E.E. Schilling)

Figure 31: Trillium maculatum (Mt. Cuba Center)

Figure 29: Trillium ludovicianum (H. and C. Nourse)

Figure 32: Trillium nivale (Mt. Cuba Center)

Figure 33: Trillium oostingii (L.L. Gaddy)

Figure 36: Trillium ovatum subsp. ovatum (K. Wayman)

Figure 34: Trillium hibbersonii (E.E. Schilling) Figure 37: Trillium persistens (L.L. Gaddy)

Figure 35: Trillium ovatum subsp. oettingeri (K. Wayman)

Figure 38: Trillium petiolatum (K. Wayman)

Figure 39: Trillium pusillum var. 1 (A. Schotz)

Figure 41: Trillium pusillum var. ozarkanum (T. Littlefield)

Figure 40: Trillium pusillum var. monticulum (West Virginia Natural Heritage Program)

Figure 42: Trillium pusillum var. 5 (W. Knapp)

Figure 44: Trillium recurvatum (L.L. Gaddy)

Figure 43: Trillium pusillum var. virginianum (R. Raguso)

Figure 45: Trillium reliquum (L.L. Gaddy)

Figure 46: Trillium rugelii (L.L. Gaddy)

Figure 48: Trillium simile (Mt. Cuba Center)

Figure 47: Trillium sessile (T. Littlefield)

Figure 49: Trillium stamineum (E.E. Schilling)

Figure 50: Trillium sulcatum (E.E. Schilling)

Figure 52: Trillium texanum (Anna Strong)

Figure 53: Trillium underwoodii (H. and C. Nourse)

Figure 51: Trillium tennesseense (E.E. Schilling)

Figure 54: Trillium vaseyi (L.L. Gaddy)

Figure 55: Trillium viride (A. Floden)

Figure 56: Trillium viridescens (H. and C. Nourse)

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198. U.S. Fish and Wildlife Service. (1984). Persistent Trillium (Trillium persistens) Recovery Plan (p. 69). Atlanta, GA: U.S. Fish and Wildlife Service. Retrieved from https:// www.fs.fed.us/wildflowers/Rare_Plants/profiles/ TEP/Trillium_persistens/documents/RecoveryPlan_ Trillium_persistens.pdf

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189. O’Neill, D. (1985). Taxonomic study of Trillium ovatum forma hibbersonii. University of British Columbia, Vancouver, BC.

200. Larsen, J. A. (1923). Association of Trees, Shrubs, and Other Vegetation in the Northern Idaho Forests. Ecology, 4(1), 63–67. https://doi.org/10.2307/1929274

190. Schilling, E. E., Farmer, S. B., O’Neill, D. M., Floden, A., & Lampley, J. (In Press). Trillium hibbersonii, a phylogenetically distinct species from western North America. Systematic Botany.

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191. Taylor, T. M. C., & Szczawinski, A. F. (1974). Trillium ovatum Pursh forma hibbersonii Taylor et Szczawinski. Syesis, 7, 250.

202. Bodkin, N. L., & Reveal, J. L. (1982). A New Variety of Trillium Pusillum (Liliaceae) from the Virginias. Brittonia, 34(2), 141. https://doi.org/10.2307/2806365

192. Ware, G. (2014). Trillium hibbersoni – the fugitive species of Vancouver Island. Alpine Garden Club of British Columbia Quarterly Bulletin, 57, 71–73.

203. Bodkin, N. L., & Reveal, J. L. (1983). A New Population of Trillium pusillum var. monticulum Bodkin and Reveal (Liliaceae). Castanea, 48(2), 155–157.

193. McNeal, D. W., & Ness, B. D. (2012). Trillium ovatum subsp. oettingeri. Jepson eFlora. Retrieved August 20, 2021, from https://ucjeps.berkeley.edu/eflora/eflora_ display.php?tid=53275

204. Claggett, P., Hearn, Jr., P. P., & Donato, D. I. (2015). Historic and forecasted population and land-cover change in eastern North Carolina, 1992-2030 (USGS Numbered Series No. 2014–1125) (p. 30). Reston, VA: U.S. Geological Survey. Retrieved from http://pubs. er.usgs.gov/publication/ofr20141125

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205. Farmer, S. (2007, August 1). A Systematic Study of Trillium subgenus Delostylis (PhD Dissertation). University of Tennessee, Knoxville, TN. Retrieved from https://trace.tennessee.edu/utk_graddiss/4235

195. Greenberger, C. (2005). Endangered plants in the watershe. Chattooga Quarterl. Retrieved from http://www.chattoogariver.org/index. php?req=endangered&quart=Su2005

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196. Lowe, D. W., Matthews, J. R., & Moseley, C. J. (1990). The official World Wildlife Fund guide to endangered species of North America. Washington D.C.: Beacham Pub.

207. Knight, T. M., Dunn, J. L., Smith, L. A., Davis, J., & Kalisz, S. (2009). Deer Facilitate Invasive Plant Success in a Pennsylvania Forest Understory. Natural Areas Journal, 29(2), 110– 116. https://doi.org/10.3375/043.029.0202

197. Patrick, T. S., Allison, J. R., & Krakow, G. A. (1995). Protected plants of Georgia: an information manual on plants designated by the State of Georgia as endangered, threatened, rare, or unusual. Georgia: Georgia Department of Natural Resources, Wildlife Resources Division, Georgia Natural Heritage Program, Social Circle.

208. Mayer, J., & Brisbin, I. L. (2009). Wild Pigs: Biology, Damage, Control Techinques and Management (No. SRNL-RP-2009-00869). Available. https://doi. org/10.2172/975099

220. Frankland, F., & Nelson, T. (2003). Impacts of whitetailed deer on spring wildflowers in Illinois, USA. Natural Areas Journal, 23(4), 341–348. 221. Gilbert, M. L., & Curtis, J. T. (1953). Relation of the understory to the upland forest in the prairie-forest border region of Wisconsin. Trans. Wisc. Acad. Sci. Art. Lett, 42, 183–95.

209. Roe, G. F. (1978). Additions to the Range of Trillium pusillum. Castanea, 43(3), 187–191. 210. Swick, E. N. (2019, May 4). Ecological Investigation of a Population of Trillium pusillum at Redstone Arsenal, Alabama (Masters Thesis). Auburn University, Auburn, AL.

222. Moore, J. E., Franklin, S. B., Wein, G., & Collins, B. S. (2012). Long-term population demography of Trillium recurvatum on loess bluffs in western Tennessee, USA. AoB PLANTS, 2012. https://doi.org/10.1093/ aobpla/pls015

211. United States Census Bureau. (2019). TIGERweb Application. TIGERweb Online APplication. Retrieved December 5, 2019, from https://tigerweb.geo.census. gov/tigerwebmain/TIGERweb_main.html

223. Sawyer, N. W. (2010). Reproductive Ecology of Trillium recurvatum (Trilliaceae) in Wisconsin. The American Midland Naturalist, 163(1), 146–160. https://doi. org/10.1674/0003-0031-163.1.146

212. VDGIF. (2015). Virginia Deer Management Plan 20152024 (p. 137). Richmond, VA: Virginia Department of Game and Inland Fisheries.

224. The vPlants Project. (2019). vPlants: A virtual Herbarium of the Chicago Region. vPlants: A virtual Herbarium of the Chicago Region [Online database]. Retrieved January 7, 2019, from http://www.vplants. org

213. Andre, C. S., Wait, D. A., & Anderson, W. B. (2005). Ecology of three populations of the rare woodland perennial, Trillium pusillum Michaux (Liliaceae) in southwestern Missouri. Missouriensis, 26, 7–21.

225. Mandel, J. R., Major, C. K., Bayer, R. J., & Moore, J. E. (2019). Clonal diversity and spatial genetic structure in the long-lived herb, Prairie Trillium. PLOS ONE, 14(10), e0224123. https://doi.org/10.1371/journal. pone.0224123

214. Radford, A. E., Ahles, H. E., & Bell, C. R. (1968). Manual of the vascular flora of the Carolinas. Chapel Hill, NC: University of North Carolina Press. 215. Robinson, A. F. (1980). Endangered and threatened species of the Southeastern United States including Puerto Rico and the Virgin Islands (U.S. Forest Service General Report No. SA-GA 7). US Forest Service.

226. Caspary, M., & Rickard, J. (2016). Assessing Conserved Populations of the Rare Relict Trillium (Trillium reliquum). Natural Areas Journal, 36(1), 59. https://doi.org/10.3375/043.036.0111

216. Steyermark, J. A. (1963). Flora of Missouri. Ames, IA: Iowa State University.

227. Gonzales, E., & Hamrick, J. L. (2005). Distribution of genetic diversity among disjunct populations of the rare forest understory herb, Trillium reliquum. Heredity, 95(4), 306–314. https://doi.org/10.1038/ sj.hdy.6800719

217. Timmerman-Erskine, M., Ballenger, J., Dute, R. R., & Boyd, R. S. (2003). Allozyme Investigation of the Trillium pusillum Michaux Complex (Trilliaceae): Taxonomic and Conservation Implications. The Journal of the Torrey Botanical Society, 130(1), 1–10. https://doi.org/10.2307/3557519

228. IUCN & UNEP-WCMC. (2020). The World Database on Protected Areas (WDPA). Cambridge, UK: UNEPWCMC/ IUCN World Commission on Protected Areas (WCPA). Retrieved from www.wdpa.org

218. Pyne, M. (1992). Guide to rare plants - Tennessee Division of Forestry District 3. Nashville: Tennessee Department of Agriculture, Division of Forestry.

229. Kartesz, J. T. (2015). The Biota of North America Program (BONAP). Taxonomic Data Center. Retrieved January 18, 2019, from http://www.bonap.net/tdc

219. Weakley, A. S. (1996). Flora of the Carolinas, Virginia, and Georgia (Working Draft No. Working Draft of 23 May 1996) (p. Unpaginated). Chapel Hill, NC: The Nature Conservancy, Southeast Regional Office, Southern Conservation Science Dept.

230. U.S. Fish and Wildlife Service. (2015). Relict Trillium (Trillium reliquum) 5-Year Review: Summary and Evaluation. Athens, GA: U.S. Fish and Wildlife Service, Southeast Region. Retrieved from https://ecos.fws. gov/docs/five_year_review/doc4479.pdf 77

231. U.S. Fish and Wildlife Service. (1990). Recovery Plan for Relict Trillium (Trillium reliauum Freeman) (p. 34). Atlanta, GA: U.S. Fish and Wildlife Service.

242. Krapfl, K. J., Holzmueller, E. J., & Jenkins, M. A. (2011). Early impacts of hemlock woolly adelgid in Tsuga canadensis forest communities of the southern Appalachian Mountains. The Journal of the Torrey Botanical Society, 138(1), 93–106. https://doi. org/10.3159/10-RA-031.1

232. Hughes, L., Westoby, M., & Jurado, E. (1994). Convergence of Elaiosomes and insect Prey: Evidence from ant Foraging Behaviour and Fatty Acid Composition. Functional Ecology, 8(3), 358–365. https://doi.org/10.2307/2389829

243. Erlandson, S. K. (2018). History, dispersal limitation, and environment shape the current and future ranges of forest herbs of the Southern Appalachians (PhD Thesis). University of Minnesota.

233. White, P. S., & Wofford, B. E. (1984). Rare Native Tennessee Vascular Plants in the Flora of Great Smoky Mountain National Park. Journal of the Tennessee Academy of Science, 59(3), 61–64.

244. U.S. Forest Service. (2001). Draft Environmental Impact Statement: Natural Area Trails Project: Shawnee National Forest. United States Department of Agriculture, Forest Service.

234. Gonzales, E., Hamrick, J. L., & Smouse, P. E. (2008). Comparison of clonal diversity in mountain and Piedmont populations of Trillium cuneatum (Melanthiaceae-Trilliaceae), a forest understory species. American Journal of Botany, 95(10), 1254– 1261.

245. Yatskievych, G. (1999). Steyermark’s Flora of Missouri, Volume 1 (Revised edition.). St. Louis, Mo: Missouri Botanical Garden Press. 246. Correll, D. S., & Johnston, M. C. (1970). Manual of the vascular plants of Texas. Contributions from Texas Research Foundation. A series of botanical studies, 6.

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Appendix A: All Red List Category and Criteria Designations Taxon Name

Red List Taxon Rank

Red List Category

Red List Criteria

Pseudotrillium rivale

Species

B1ab(iv)

Trillium albidum

Species

Trillium angustipetalum

Species

Trillium catesbaei

Species

Trillium cernuum

Species

Trillium chloropetalum

Species

Trillium cuneatum

Species

Trillium decipiens

Species

Trillium decumbens

Species

Trillium delicatum

Species

Trillium discolor

Species

Trillium erectum

Species

Trillium flexipes

Species

Trillium foetidissimum

Species

Trillium georgianum

Species

B1ab(iii,v)+2ab(iii,v)

Trillium gracile

Species

B2b(iii)

Trillium grandiflorum

Species

Trillium kurabayashii

Species

Trillium lancifolium

Species

B2ab(iii,v)

Trillium ludovicianum

Species

Trillium luteum

Species

Trillium maculatum

Species

Trillium nivale

Species

Trillium oostingii

Species

Trillium ovatum

Species

Trillium ovatum

Trillium crassifolium

Variety

Trillium ovatum

Trillium hibbersonii

Variety

Trillium ovatum subsp. oettingeri

Subspecies

Trillium ovatum

Trillium scouleri

Subspecies

Trillium ovatum

Trillium parviflorum

Species

C2a(i)

Trillium persistens

Species

Red List Complex Designation

B1ab(iii,v)

B1ab(v)+2ab(v)

Trillium ovatum

Appendix A: All Red List Category and Criteria Designations Taxon Name

Red List Taxon Rank

Red List Category

Trillium petiolatum

Species

Trillium pusillum var. monticulum

Variety

Trillium pusillum var. ozarkanum

Variety

Trillium pusillum

Trillium pusillum var. pusillum

Variety

Trillium pusillum

Trillium pusillum var. virginianum

Variety

Trillium pusillum var. 1

Variety

Trillium pusillum var. 3

Variety

B2ab(iii);D

Trillium pusillum

Trillium pusillum var. 4

Variety

B1ab(i,iii,iv,v)

Trillium pusillum

Trillium pusillum var. 5

Variety

B1ab(iii)

Trillium pusillum

Trillium recurvatum

Species

Trillium reliquum

Species

Trillium rugelii

Species

Trillium sessile

Species

Trillium simile

Species

Trillium stamineum

Species

Trillium sulcatum

Species

Trillium tennesseense

Variety

B1ab(iii,iv,v)+2ab(iii,iv,v)

Trillium texanum

Species

B2ab(iii)

Trillium underwoodii

Species

Trillium undulatum

Species

Trillium vaseyi

Species

Trillium viride

Species

Trillium viridescens

Species

Red List Criteria

Red List Complex Designation

B1ab(iii)+2ab(iii)

Trillium pusillum

B1ab(iii)

Trillium pusillum Trillium pusillum

B1ab(iii,v)+2ab(iii,v)

B1ab(iii)

Trillium lancifolium

Appendix B: All NatureServe Rankings NatureServe Complex Designation

Taxon Name

NatureServe Taxon Rank

NatureServe Rank

Pseudotrillium rivale

Species

Trillidium undulatum

Species

Trillium albidum

Species

Trillium albidum

Trillium albidum subsp. albidum

Subspecies

Trillium albidum

Trillium albidum subsp. parviflorum

Subspecies

Trillium albidum

Trillium angustipetalum

Species

Trillium catesbaei

Species

Trillium cernuum

Species

Trillium chloropetalum

Species

Trillium crassifolium

Species

Trillium cuneatum

Species

Trillium decipiens

Species

Trillium decumbens

Species

Trillium delicatum

Species

Trillium discolor

Species

Trillium erectum

Species

Trillium flexipes

Species

Trillium foetidissimum

Species

Trillium georgianum

Species

Trillium gracile

Species

Trillium grandiflorum

Species

Trillium hibbersonii

Species

Trillium kurabayashii

Species

Trillium lancifolium

Species

Trillium ludovicianum

Species

Trillium luteum

Species

Trillium maculatum

Species

Trillium nivale

Species

Trillium oostingii

Species

Trillium ovatum

Species

Trillium ovatum var. oettingeri

Variety

Trillium ovatum var. ovatum

Variety

Trillium persistens

Species

Appendix B: All NatureServe Rankings NatureServe Complex Designation

Taxon Name

NatureServe Taxon Rank

NatureServe Rank

Trillium petiolatum

Species

Trillium pusillum

Species

Trillium pusillum

Trillium pusillum var. monticulum

Variety

Trillium pusillum

Trillium pusillum var. ozarkanum

Variety

Trillium pusillum

Trillium pusillum var. pusillum

Variety

Trillium pusillum

Trillium pusillum var. virginianum

Variety

Trillium pusillum

Trillium pusillum var. 1

Not Accepted

GNR

Trillium pusillum

Trillium pusillum var. 3

Not Accepted

GNR

Trillium pusillum

Trillium pusillum var. 4

Not Accepted

GNR

Trillium pusillum

Trillium pusillum var. 5

Not Accepted

GNR

Trillium pusillum

Trillium recurvatum

Species

Trillium reliquum

Species

Trillium rugelii

Species

Trillium scouleri

Species

Trillium sessile

Species

Trillium simile

Species

Trillium stamineum

Species

Trillium sulcatum

Species

Trillium tennesseense

Species

Trillium texanum

Species

Trillium underwoodii

Species

Trillium vaseyi

Species

Trillium viride

Species

Trillium viridescens

Species

Appendix C: Red List Categories and Criteria SUMMARY OF THE FIVE CRITERIA (A-E) USED TO EVALUATE IF A TAXON BELONGS IN AN IUCN RED LIST THREATENED CATEGORY (CRITICALLY ENDANGERED, ENDANGERED OR VULNERABLE).1 A. Population size reduction. Population reduction (measured over the longer of 10 years or 3 generations) based on any of A1 to A4 Critically Endangered

Endangered

Vulnerable

≥ 90%

≥ 70%

≥ 50%

A2, A3 & A4

≥ 80%

≥ 50% ≥ 30% (a) direct observation [except A3] (b) an index of abundance appropriate to the taxon (c) a decline in area of occupancy (AOO), extent of occurrence based on (EOO) and/or habitat quality any of the (d) actual or potential levels of following: exploitation (e) effects of introduced taxa, hybridization, pathogens, pollutants, competitors or parasites.

A1 Population reduction observed, estimated, inferred, or suspected in the past where the causes of the reduction are clearly reversible AND understood AND have ceased. A2 Population reduction observed, estimated, inferred, or suspected in the past where the causes of reduction may not have ceased OR may not be understood OR may not be reversible. A3 Population reduction projected, inferred or suspected to be met in the future (up to a maximum of 100 years) [(a) cannot be used for A3]. A4 An observed, estimated, inferred, projected or suspected population reduction where the time period must include both the past and the future (up to a max. of 100 years in future), and where the causes of reduction may not have ceased OR may not be understood OR may not be reversible.

B. Geographic range in the form of either B1 (extent of occurrence) AND/OR B2 (area of occupancy) Critically Endangered

Endangered

Vulnerable

B1. Extent of occurrence (EOO)

< 100 km²

< 5,000 km²

< 20,000 km²

B2. Area of occupancy (AOO)

< 10 km²

< 500 km²

< 2,000 km²

≤5

≤ 10

AND at least 2 of the following 3 conditions: (a) Severely fragmented OR Number of locations

(b) Continuing decline observed, estimated, inferred or projected in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) area, extent and/or quality of habitat; (iv) number of locations or subpopulations; (v) number of mature individuals (c) Extreme fluctuations in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) number of locations or subpopulations; (iv) number of mature individuals C. Small population size and decline Number of mature individuals

Critically Endangered

Endangered

Vulnerable

< 250

< 2,500

< 10,000

25% in 3 years or 1 generation (whichever is longer)

20% in 5 years or 2 generations

10% in 10 years or 3 generations

(whichever is longer)

AND at least one of C1 or C2 C1. An observed, estimated or projected continuing decline of at least (up to a max. of 100 years in future): C2. An observed, estimated, projected or inferred continuing decline AND at least 1 of the following 3 conditions: (a) (i) Number of mature individuals in each subpopulation (ii) % of mature individuals in one subpopulation =

≤ 50

≤ 250

≤ 1,000

90–100%

95–100%

100%

Critically Endangered

Endangered

< 50

< 250

Critically Endangered

Endangered

(b) Extreme fluctuations in the number of mature individuals D. Very small or restricted population D. Number of mature individuals D2. Only applies to the VU category Restricted area of occupancy or number of locations with a plausible future threat that could drive the taxon to CR or EX in a very short time.

Vulnerable D1.

< 1,000

D2.

typically: AOO < 20 km² or number of locations ≤ 5

E. Quantitative Analysis

Indicating the probability of extinction in the wild to be:

≥ 50% in 10 years or 3 ≥ 20% in 20 years or 5 generations, whichever generations, whichever is longer (100 years is longer (100 years max.) max.)

Vulnerable ≥ 10% in 100 years

Use of this summary sheet requires full understanding of the IUCN Red List Categories and Criteria and Guidelines for Using the IUCN Red List Categories and Criteria. Please refer to both documents for explanations of terms and concepts used here.

Appendix D: Table of Common Names Used in Text Common Name

Latin Name

Author

American Ginseng

Panax quinquefolius

Azaleas

Rhododendron spp.

Bigleaf Maple

Acer macrophyllum

Pursh.

Black Gum

Nyssa sylvatica

Marshall

Blowflies

Calliphoridae

Brauer & Bergenstamm, 1889

Burning Bush

Euonymus alatus

(Thunb.) Rupr.

Bush Honeysuckle

Lonicera maackii

(Rupr.) Maxim

Chinese Privet

Ligustrum sinense

Lour.

Cougar

Puma concolor

Linnaeus, 1771

Douglas-fir

Pseudotsuga menziesii

(Mirb.) Franco

Elk

Cervus canadensis

(Erxleben, 1777)

English Ivy

Hedera helix

Garlic Mustard

Alliaria petiolata

(M. Bieb.) Cavara & Grande

Gray Wolf

Canis lupus

Linnaeus, 1758

Green Ash

Fraxinus pennsylvanica

Marshall

Hemlock Woolly Adelgid

Adelges tsugae

(Annand, 1928)

Himalayan Blackberry

Rubus armeniacus

Focke

Japanese Honeysuckle

Lonicera japonica

(Lour.) Merr.

Japanese Stiltgrass

Microstegium vimineum

(Trin.) A.Camus

Kinugasasō

Paris japonica

Franch.

Kudzu

Pueraria montana

Thunb.

Mother Wort

Leonurus cardiaca

Oak

Quercus spp.

Pig

Sus scrofa

Linnaeus, 1758

Raspberry

Rubus iadeus

Red Alder

Alnus rubra

Bong.

Red Maple

Acer rubrum

Shepherd's Purse

Capsella bura-pastoris

Moench.

Silverberry

Elaeagnus commutata

Bernh. ex Rydb.

Sitka Spruce

Picea sitchensis

Bong.

Trifoliate Orange

Poncirus trifoliata

(L.) Raf.

Appendix D: Table of Common Names Used in Text Common Name

Latin Name

Author

Western Hemlock

Tsuga heterophylla

Sarg.

Western Red Cedar

Thuja plicata

Donn ex D.Don

White-tailed Deer

Odocoileus virginianus

(Zimmerman, 1780)

Winter Creeper

Euonymus fortunei

(Turcz.) Hand.-Mazz.

Yarrow

Achillea millefolium

The Conservation Status of Trillium in North America

For further information, please contact:

Mt. Cuba Center 3120 Barley Mill Rd. Hockessin, DE 19707

Tel: (302) 239-4244 info@mtcubacenter.org https://mtcubacenter.org/

The Conservation Status of Trillium in North America

Articles inside

Trillium viridescens

A note on the taxonomy of Trillium

Major Threats

The Trillium Collections at Mt. Cuba Center

On western Trillium

Executive Summary

Ending the Trillium Trade in Commercial Herbal Products

Foreword

Mapping